I noticed a substantial similarity between Stargate SG-1 episode Collateral Damage and a Star Trek - Voyager episode Ex Post Facto.

I won't go into details describing the episodes to avoid having spoilers, it is possible to see the plot on the linked wiki pages. It is sufficient to say that I practically knew the entire plot of one just because I previously watched another.

Is Stargate episode meant to be an homage to the Voyager episode? Maybe both shows were basing the script on another older story? Or is it just a mere coincidence?

Parts of the plot that apply to both episodes:


Paris/Cameron goes to an alien world in order to exchange some technology. In Voyager it was some spare parts they needed for the ship, in SG-1 it was the memory device itself.


He cooperates with a distinguished elderly scientist who invites him to his home.


The scientist has a beautiful wife who tries to seduce our main character.


They share a drink, he passes out. THe next thing he knows is that the scientist is dead and he is the main suspect. No one on the planet believes him, but Voyager/SG-1 team are doing their best to prove his innocence.


Additionally, there is a memory recording, playback and manipulation technology, which is used on the accused character. But, as you can see that tech is far from being the most important part of the plot which is similar.

  • 1
    I just saw Collateral Damage and drew the same connection immediately. I bet it was just lazy writing on the part of the Star Gate writing staff, frankly. The SG1 writers really seemed to start sputtering on ideas at different points toward the end of the series. Though I felt the overall story-arcs were usually of pretty good quality. Commented Dec 3, 2011 at 20:56
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    SG-1 did like to make fun of a lot of sci-fi memes. They had to have time travel, body-swapping, aging/de-aging, ghosts, and memory manipulation. Memory manipulation seems to be one of the lesser-used ones but it's still there.
    – Chad Levy
    Commented Dec 3, 2011 at 21:41
  • 4
    @Paperjam: Yes, they even lampshaded most of it in episode 200. However, this isn't just a theme, it's pretty much the entire plot of the episode. Commented Dec 3, 2011 at 21:47
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    Two even more similar episodes are Workforce (Voyager 7x16) and Beneath the Surface (SG1 4x10). They aired less than a year apart to boot. Commented Jan 3, 2012 at 4:12
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    "Ex Post Facto" is a recycle of a Star Trek TNG episode called "A Matter of Perspective." Commented Jan 1, 2017 at 20:58

2 Answers 2


I would say that it is more likely coincidence that these two episodes are similar. They each just happened to use the same pairing of two very common tropes/plot lines:

After reading through the plots of both episodes, I couldn't help but think of another example of this common storyline that predates both: the TNG episode "A Matter of Perspective". Here's how it stacks up against the plot points you listed above:

  1. The Enterprise goes to the Tanuga IV Research Station to inspect the Starfleet-funded research being done on a Krieger wave converter.

  2. Riker is sent to make a progress report on this research, which is being done by Dr. Nel Apgar.

  3. There ends up being some attraction between Riker and the doctor's wife, Manua, and Dr. Apgar walks in on them in an embrace. It is not altogether clear whether Riker or Manua (or likely both) is the instigator of said uncomfortable situation, as this part of the story is told from each one's recollection.

  4. When Riker beams off the station after hearing everything he needs to for his progress report, the station explodes. Riker is later charged with murder when an energy discharge is found to have occurred mid beam-out, coming from Riker's position and presumably from a phaser. It is ultimately deduced by Data, La Forge, and Wesley that the explosion of the station was actually caused by Dr. Apgar when he tried to kill Riker by dispersing his transporter pattern with a focused beam of energy, which reflected off the transporter beam and hit the reactor on the research station.

  5. There was no memory-manipulation technology in the episode, but the holodeck was used to visualize reconstructions of the testimonies from the different witnesses (and ultimately to solve the mystery). In a sense, the holodeck and memory-manipulation technologies served a similar purpose: they both showed that personal recollections can be untrustworthy and have less evidentiary value when compared to good old-fashioned deduction and investigation.

  • +1, thank you - this is exactly what I was trying to get at with my answer, but didn't know the specific tropes!
    – Izkata
    Commented Dec 6, 2011 at 1:18
  • This seems the most plausible. Using same two tropes which happened to be central to the plot would result in a very similar episodes. Commented Dec 10, 2011 at 8:17

It's been a long while since I've seen Collateral Damage, so I'll be basing it off of the plot on the page.

  1. SG-1 knew that the Galaran technology could modify and create memories, that was unknown in the Voyager episode
  2. Official usage of the technology was completely different. (SG1: Passing knowledge to the next generation, VOY: Used in criminal investigations/punishments)
  3. The memory used was completely different. (Paris was forced to relive the victim's death, Mitchell remembered doing the murder)
  4. The plot was exposed in SG1 by comparing other memories and physiological responses to it; in VOY, Tuvok figures it out based on inconsistencies in the memory itself.
  5. In SG1, Marell removed his own memories of the event. The doctor who did the memory replacement in VOY did not.
  6. Oh, and a major plot point of the Voyager episode is missing: What about the tactical information embedded in the memory, and that the real perpetrator betraying his people?

Memory manipulation is fairly common in sci-fi. Just because similar plot elements are used does not mean either one copied off of the other.

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    I agree, but the technology is not the only thing similar. See my edit. Commented Dec 4, 2011 at 0:46
  • @GoranJovic In Farscape, there was an episode where Zhaan was framed for a murder, and the only ones who believed she was innocent were her crew. The memory-manipulation device may have been absent, but there's another series borrowing a similarly common plot for one of their episodes.
    – Izkata
    Commented Dec 4, 2011 at 4:29
  • Your Farscape example is only half of #4 from my edit. SG-1 episode has the entire sequence in that order. Commented Dec 5, 2011 at 13:08

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