How did Ferretti know they couldn't go backwards through the Stargate?

Question

In the original Stargate movie, after they arrive on Abydos and discover Daniel needs to find the symbols to reactivate the gate, the following exchange occurs between Brown and Ferretti (around 38:30):

BROWN: If we're not back soon, they'll just turn on the 'gate from the other side.

FERRETTI: Oh, no. It doesn't work that way. You see, if you don't turn it on from here, we're screwed, okay? So I'm telling you guys, we're not going anywhere!

How could Ferretti have known, or why would he have assumed, that travel through the wormhole was one directional?

As Stargate SG-1 would later expand upon, his assumption was 100% correct.

But from the film canon itself, I don't remember anything that would have established that fact up to that point.

Did I miss something, or is a plot hole? Perhaps a technique to inform the audience they had determined this off screen? For that matter, if it had already been determined offscreen, why would Ferretti have known but not Brown?

Answer 1

This seems to be a hangover from the original screenplay, where the gate was theoretically capable of being opened (and traversed) from both sides, but couldn't transfer people because the beam length was so short that anything entering from the Abydos side wouldn't make it back to Earth before the gate shut down.

The plan was to open the gate for the minimum period possible and then close and evacuate the missile silo entirely. They'd only unlock if the team made it back safely under their own steam.

GENERAL WEST: But I won't send our boys over there if I'm not absolutely sure I can bring 'em back.

ASSISTANT LIEUTENANT: We know the beam will only stay connected for a short amount of time. After the ring shuts itself down, we'll have to re-establish the beam from the other side.

DANIEL: We could re-establish from here.

GENERAL WEST: Once our team goes through, this place will be evacuated and sealed. We don't know what might come through from the other side.

DANIEL: So you want me to go over with the team, re-align the Star Gate and bring everyone back home.

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In the movie, it would appear that Feretti is the only one who bothered to read the briefing materials. It was established in the previous scene that Daniel needed to open the gate from the other side.

WEST: That's why we may have to abort. This project is for naught without a reconnaissance mission.

JOHNSON: Once on the other side, we'd have to decipher the markings on their 'gate, and in essence dial home in order to bring the team back.

WEST: Based on this new information, I don't see how we can do that.

The official novelisation agrees with this sentiment. Johnson (AKA Reilly) is basically a big dumb dope who didn't do his homework.

'He's right," agreed Reilly, looking up from hammering the tent spike. "If we're not back soon, they'll just turn the Gate on from Earth." "Look, dimwit," Feretti began to lecture Reilly, "ask yourself how you got here. Was it a two-lane highway? No. You got blasted through this weird energy cannon at about fifty billion miles an hour, turning you into a higgin' zeromass, interstellar Gumby, okay? Now think: how many directions were you going at once? One! One direction.

Now, not only is the silo emptier than a church on payday, but even if those science boys do go back inside and even if they do turn that goddamn galactic garbage disposal back on, what are you gonna do? Swim against the current?"

Science Officer Brown was listening. He looked up from assembling the dish scanner and said, "Feretti"s right. The beam moves one direction at a time. This is deep shit we're in."