Revealing mistake: In this very-low-budget but star-studded flick about UFO contactees and cattle mutilations, Jan Michael Vincent's semi-auto handgun runs out of ammo during a firefight after firing only 3 rounds (the slide locks open, indicating the magazine is empty). Without reloading or racking the slide, Vincent continues firing 5 more rounds; but we see again, in close-up, that the slide is locked open, indicating an empty magazine. (01:00:55)
Factual error: The Hillman Minx car seen picking up Brits at Conchin railway station is at least a 1945 model. The film is set in 1943.
Continuity mistake: Kenny must be fast. He's disguised as the female assistant at one point then minutes later he's disguised in the Groucho Marx costume.
Suggested correction: It's not a full costume. Kenny steals the mask and what looks like a small waistcoat (leaving even the hat). It's not implausible that Kenny made a quick change (probably after killing Ed) to formal wear (which isn't what Ed was wearing). After Ed's murder, Kenny-as-Ed appears briefly only from the waist up (showing only the stolen mask and waistcoat), and then doesn't appear again for quite a few minutes, more than enough time to change to the formal wear.
Other mistake: The alligator baits Col. Brock through a feat of chinese shadow puppetry certainly quite unlikely for the intelligence shown in the rest of the movie, and inconsistent with the movements he's capable of, not to mention the fact that he would have needed to perfectly abscond covering himself in trash bags super-fast, flawlessly, silently. (01:05:00)
Continuity mistake: When Mickey gets into the '57 Chevy to "test drive" it, there is no gear shift lever on the steering column. The camera then shows him buckling his seat belt, and when it returns to the previous angle, there is that missing shift lever.
Factual error: There appears to be a pickup truck parked by a barn in the background when Steve McQueen is standing by his horse, talking to Linda Evans. (00:19:00 - 00:20:00)
Revealing mistake: Linderman refuses Clifford's offer to be his personal bodyguard from Moody's gang, and leaves. As Clifford walks by the students practicing their violins, playing Mozart, their bow movements do not match the music.
Factual error: When the Peanuts gang got to Victoria station, Travel Center is spelled the American way. Since it's England it should be "centre" (00:24:55)
Continuity mistake: When Voltan barges into the convent with his men the nuns go from behind their individual pews to huddled in a group behind the Abbess between shots. (00:11:06)
Continuity mistake: As the survivors are first seen from the deck of the Death Ship, they are up and paddling. As the scene shifts to their view looking up at the ship, they were apparently asleep, except for the captain.
Continuity mistake: When Cole and the halfbreed duel with knives, the fabric they hold in their mouths as a tether keeps flipping over, meaning the end of the cloth hangs out the left side of the mouth, then the right, and left again - several times for both actors - even tho the fight is continuous and they make no moves that would change this.
Continuity mistake: When Ira and Glenda are discussing Nick, who is hiding under the bed, Ira briefly stands on Nicks right-hand pinky finger. After Ira has walked away, under the bed Nick grimaces while holding his left-hand pinky finger.
Visible crew/equipment: In the bar fight scene, the camera crew is visible right after Lefty hits one of the bar patrons.
Continuity mistake: Gus Soltic at the beginning of the movie pours ketchup on the eggs. When he's done, he moves away the bottle in one shot, but it's still vertical above the eggs in the next shot. (00:02:00)
Revealing mistake: At the end of the film, it's obvious the ground that Phil falls into is just some mats dressed up in fake snow.