Revealing mistake: When Richard first wakes up after travelling through time, he's supposed to be lying on a couch. Yet there is a wall behind him. It's blatantly obvious that it's the same shot from the modern bedroom, and all they did was change the lighting. (00:33:45)
Visible crew/equipment: In "Whenever You're Away From Me", Kira and Danny dance by a mirror, where you can see the cameraman. (00:32:10)
Revealing mistake: In the dance sequence, we see Elaine twirling Ted around and throwing him into the crowd. Watch the top-right-corner of your screen, as the stunt-double lands in the audience you can see Robert Hays (Ted Striker) in the top-right-corner waiting to pop out. (00:19:10)
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)
Continuity mistake: There is a scene in which it is raining quite heavily and Em and Richard are inside the hutch. Richard is playing Pop Goes The Weasel over and over which annoys Em. She stabs him in the foot and he chases her outside. In this scene she is wearing a strapless dress but when he catches her and pins her down on the sand she is wearing a lacey jacket (she didn't have time to change) and there are no clouds or rain. The sand doesn't seem to be very wet either, despite the fact that it was raining heavily a few minutes ago. (00:41:10)
Visible crew/equipment: When Superman is fighting Non under the New York Streets (in the sewers), manhole covers start to jet up in the sky. When the first manhole cover shoots up you can quite clearly see the gas tube in the hole and the gas cylinder attached to the cover.