Revealing mistake: As the spaceship heads back into space, it leaves the same way that it crashed - they reversed the film. (01:18:30)
Revealing mistake: Near the beginning, when the giant fiery comet hits, it goes behind a hill, yet you can still see the glow of the comet through the hill and the shops in front of the hill, revealing it is a backdrop. (00:04:20)
Revealing mistake: In the beginning where Vincent Price is brawling with his business partner, his partner throws a pipe or bar at him. Price ducks and the bar hits something that the camera was connected to, because the scene jerks.