I am reluctant to say that anything about the prequel is better than the original movie - John Carpenter's film is a classic, and in my opinion, the best horror/science fiction movie ever made; whereas the prequel is mediocre at best. Pretty much everything about the original is superior to the prequel. This, however, might be the only exception to that rule.
The 1982 film doesn't really give us much information about what happened in the Norwegian camp, including the unfortunate individual with the horrendous wounds to his wrists and throat. The Norwegian camp is merely a backdrop, and we only spend about 5 minutes there. Everything we see is there purely for dramatic effect and to shock us. The movie's special effects mastermind, the immortal genius Rob Bottin, is known for his over-the-top visual effects, and it was probably just second nature for him to make the wounds as severe as possible. And it works, quite frankly, within the context of the movie as a whole.
But when it was decided that a prequel should be made, and that the prequel would be set in the Norwegian camp, the writers were faced with the formidable challenge of figuring out what happened there, and how all the things we see in the original got to where we saw them. Again, this included the guy with the slit throat.
When the writers began to come up with an explanation for how the guy with the slit throat got that way, they realized that the wounds were so profound that they actually seemed implausible at the very least. As you have pointed out, it would be almost impossible for a person to slit their wrists, then slice their throat open so badly that they almost decapitate themselves. The writers, therefore, had to change the original imagery around a bit, just to make the scene more believable.
The writer of the final script, Eric Heisserer, visited a fan forum and commented on a thread about continuity issues he had to deal with:
Hey gang, I hope you don't mind me dropping by. I should have thought to dig in many moons ago and answers some questions when they were actively discussed, but let me grab a couple of minutes here to answer some questions and try to honor your intelligent discussion with some discoveries of my own.
First I'll be upfront that my approach to these bits of continuity are from a story and logic perspective, and do not necessarily match what others believe. The director may have his own reasons for this or that, and maybe they match my own or maybe it's a different approach.
As to the continuity of the thermite detonating over the ship in the Carpenter film versus the ship's own thrusters melting the ice...
I spent a few weeks interviewing scientists in this and relative fields, including a forensic archaeologist. My father was a classics professor for thirty years, so I had a need to appeal to the scientific community as a way of respecting him. What I learned from the scientists was this: Using thermite or similar explosives to detonate the ice directly over the ship is a "remarkably stupid idea that no scientist of merit would choose to do." It endangers the very artifact or site you're trying to access. Improperly done, you can have a few million tons of ice come down and destroy the thing you're trying to get to. The way it's done is: You dig in (with explosives, perhaps) nearby and find a route on a horizontal path to the ship in order to slowly excavate it or explore it. If you need to come in from the top, you only do that with a tunnel using drills. But a route from the side is the scientifically sound concept.
So how could we make sure our scientists were smart here, and still keep in continuity with Carpenter's movie? Well, actually, it does work. For so long I had thought that we saw footage of the team placing the charges directly above the site and then detonating them, but that's not quite true. We get a clip of them marking with flags the diameter of the ship, and then there's a skip to footage of an explosion, but we don't know exactly where. It's easy to believe we are looking at the same location, but it's also possible they were detonating the thermite on a shelf nearby to gain access to that ice cave.
So that was my way in to building a story that kept with the footage from the 1982 movie while also keeping it scientifically sound.
Of course I ran into the same problem with that damned block of ice. My two archaeologists watched the movie and had me pause it there, asking "Why would they dig out the creature that way? That makes no sense." I asked them to explain, and they said it was a similar principle to the space ship: If you go in from the top to dig out the creature from the ice, you're making the job ridiculously hard on yourself. You have to lift it up. It requires more equipment. Whereas someone with a little smarts would instead dig in through the side. That's where the director had the idea of the creature bursting out on its own through the top, so we wouldn't have to shine a light on the rather awkward and unwieldy approach to removing the Thing.
Sometimes dealing with the smart science led to continuity problems elsewhere, and obviously I had zero control of the story once it got into production, but I thought I'd shed some light on the origins of these solves and the investigation into the logic of it all.
The fan site in question is called Outpost 31, and this issue is addressed in the FAQ:
Q: What about the suicide victim at the Norwegian camp?
A: The apparent suicide found by Mac and Copper brings up a couple of issues. First, was it a true suicide? In The Thing (2011), this character is English and his name is Colin. Although it seems to have taken place in response to the threat posed by the Edvard-Thing, the suicide act itself happens off-screen. Questions have been raised by some viewers over whether or not a person could inflict such a deep throat gash upon himself. To these fans, the throat cut is too suspicious.
The Outpost 31 thread mentioned above also contains this excerpt from a now-deleted review of the 2011 prequel on IMDB:
"When the Americans find Colin's body in the 1982 film, his slashed throat had a ridiculous chunk of flesh missing from it. To the point he was near decapitation. In this film, the wound looks much more like a simple deep cut. In both films it's implied he slashed his own throat (and possibly his wrists too) this alteration was likely done for realism as somebody likely wouldn't be able to nearly cut their own head off with a straight razor".
From a rundown of the movie on the website "Pop Apostle":
The shot of Colin, who has committed suicide by slashing his wrist and throat is a bit different than the shot of the suicide man seen in the 1982 film. He is slouched farther down in his chair here and the radio equipment is not as badly damaged. It almost seems as if the 1982 film wanted to give the impression that someone had deliberately sabotaged the equipment (as occurs at Outpost 31); that scenario does not occur in this prequel. The face is different, of course, too, but they needed to match the current actor, so that's understandable.
The website Bloody Disgusting did an interview with the writer, Eric Heisserer, in which he talks about the challenges of writing a movie backwards, so to speak:
One of the best parts about making a prequel is that a writer gets to really dissect the first film in order to construct a backstory.
“It’s a really fascinating way to construct a story because we're doing it by autopsy, by examining very, very closely everything we know about the Norwegian camp and about the events that happened there from photos and video footage that’s recovered,” he continues, “from a visit to the base, the director, producer and I have gone through it countless times marking, you know, there’s a fire axe in the door, we have to account for that…were having to reverse engineer it, so those details all matter to us `cause it all has to make sense.”
“We explain how it got there,” he continues referring to the axe, adding that he found a way to bring suspense back to the film. “We’re finding so much from Carpenter’s movie that you think you’ve seen, but in actuality it allows us to come up with certain twists on what we have that will allow people to be on the edge of their seat, and not know who’s going to make it and who’s not.”
Another interview with Heisserer, this one from the site Quiet Earth:
Q: I read one plot synopsis that said the film was completely from the Norwegians' point of view, on their base, pre-burn down. Then I read another synopsis that said the audience sees the aftermath of the film's events, including the axe in the door, and they're figuring it out after it happened — almost like a crime scene. If the latter synopsis is accurate, will you be utilizing flashbacks to tell The Thing's prequel story?
A: No it's not flashbacks. You're actually in the Norwegian camp, before all that stuff happens. You get to see how it happens — that's the reverse engineering there. The way we approached it was by autopsy, where the director, producers and I pored over Carpenter's film. We must have screened it two or three dozen times. And we'd freeze frames and have lengthy discussions about what evidence is there, that would lead to so much blood. It was a forensic discussion of Carpenter's films. That's probably where the whole "fire axe in the door" probably came from. Because we said, we have to justify that, we have to have a moment in our movie where you see that happen.
If we do this right — I just spoke on the phone today with [Producer] Eric Newman on the phone today, he's on set up in Toronto [and] he said things are going well. But if we can pull this off, this movie will work perfectly [as] the first half of a double feature. So that the last shot of this film will be two Norwegians and a chopper chasing after a dog. And you can plug in Carpenter's film and they will both feel and look as they have been made around the same time.
Q: What were some of the moments you noticed in John Carpenter's version that you never noticed before, after analyzing it?
A: Well there are things that definitely called attention, [such as] dealing with the body in the chair. What we didn't notice before was that it looked like both his throat and his wrists were slit. And there are a lot of papers scattered on the floor that Copper picks up. And the stuff that we looked at closely were the holes in the walls and on the ceiling, in various parts of the base. And this is how anal retentive we were, we wanted to justify what happened to cause all those holes, pieces and incidental damage. You just know some set guy that day [during the original filming] was like, "well it burned down, let's put a hole here." [Laughs].
But the one thing we're not going to pull off well, because we realized it was just unrealistic and just one of those goofs, I guess, from Carpenter's films, is when they get into that giant block of ice that's been carved out. The way it's been carved where it looks like they just dug into it like a chicken pot pie — it's impossible to get something out of the ice like that. There are so many better ways to do it. So we deviated just a little bit from there, we tried to cover our tracks a little and justified it and showed that it can still work. But yes there are a couple of things where because we were logic cops all the way through this movie there are a handful of, "Wait a minute — how come... that doesn't work at all?!"
Q: Good then — the logic cops can explain to me how someone can get a slashed throat and slashed wrists. Don't you lose dexterity, but I guess that's the mystery as to how that happened?
A: Yeah we had a problem with that as well, but hopefully we answer that and if not you can bust me on it next year.
The director, Matthijs van Heijningen, did an interview with the website Screen Rant:
Q: I know you actually used the John Carpenter film in order to construct the Norwegian base. How many times would you say that you watched that scene?
A: “We saw it like a million times to figure out the layout. But there’s a site called Outpost31.com, and they’re like hardcore geeks, and they sort of made a diagram of what they thought the layout of the Norwegian camp was. And actually it was completely accurate. So, we used that as a sort of guide, basically, to construct it.”
Q: Can you talk about the freedom that doing this as a prequel gave you as a director, rather than trying to make an actual remake of the Carpenter film? And was there talk of doing it as a remake?
A: “No, when I came aboard, it was already a prequel, and there was a script around, which I really didn’t like. One of the major problems with that script was that you already knew what the thing was, and I said that doesn’t work. There were restrictions, like we had to sort of treat it as a crime story in a sense. Like there’s all this evidence of what happened, the axe in the door, and the two-faced monster outside and certain holes in the wall. So we based our story around those pieces of evidence. That is restrictive in a way because the two-faced monster has to come out of this part of the building, because it lies on the ground in John Carpenter’s movie here. In that sense we had to really construct it around the evidence.”
It should be said that in most respects, the prequel really did do a fantastic job of making sure that the sets looked almost exactly like they did in the original. There were no measurements of the original sets, so they actually had to judge the dimensions of each room by how tall Kurt Russel is. And, incredibly, they ended up resorting to diagrams drawn by fans on the aforementioned Outpost 31 fan site.
In the end, the sets really are quite impressive in their faithfulness to the original movie. See for example these comparison shots of the room in which MacReady and Copper find the body:
Pay attention to the broken window in the background - that is not the same piece of glass, it is a painstaking reproduction of the original one.
So it would appear that the reason Colin's wounds in the original are so much worse than in the prequel is because of the different objectives and priorities between the two films. The original movie just wanted something that looked cool. But the prequel had to actually show us how the injury occurred, and that raised the issue of whether the incredibly deep gash in the original movie was even remotely plausible. The powers that be decided that no, it wasn't plausible at all.
Therefore, they made an informed decision to alter the scene slightly. The insane level of attention to detail in the other aspects of the scene suggests that making the wounds look the same was certainly possible, but the desire to make the scene believable overrode the desire for consistency in this case.
Incidentally, a scene showing Colin's death was filmed, but - along with many other scenes - was eventually dropped from the finished version of the movie due to time constraints. It is available on YouTube, albeit in an incomplete form. The plan was to add a CGI Thing into the shot, but this was never done; as a result, we see Colin reacting to a threat that isn't visible to us, although we can hear it.