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.
Revealing mistake: When Kramer is walking through the airport and all the cult members come after him and he's flipping them behind him, look down to the lower left and you can see the mat they are landing on.
Revealing mistake: Early in the movie, there are scenes of a doctor's office with a human heart bouncing on the desk and you can clearly see the string that pulls the heart.
Revealing mistake: During the disco scene, Elaine is dancing with a fisherman who was just stabbed in the back. The fisherman has a knife sticking out of his back and you can clearly see the block that the knife is stuck in protruding from his shirt. There are holes from other takes too.
Revealing mistake: During the fight between the girl scouts, one of the girls falls backwards and knocks into the camera's tripod, shaking the camera a bit.
Revealing mistake: In the disco dance sequence where Elaine is twirling, you can see the ropes that keep her attached to the camera rig.
Visible crew/equipment: Striker is in the pilot's seat and a vulture is sitting on the back of it. On the bottom-left of screen you can see someone's forearm in a white sleeve, giving the suggestion that either Randy or Elaine are standing, and leaning on the pilot seat's armrest. However, Randy is not in the cockpit and Elaine is sitting in the co-pilot's seat.
Revealing mistake: When the old woman asks Elaine about reading, if you look behind Elaine and to the upper left, you can see the scotch tape holding the set together. You have to look closely to see it.
Continuity mistake: When the 747 crashes into the terminal window, the red stripes wrap all the way around the nose of the plane. In the previous shot, the stripes came to a point and ended several feet back.
Continuity mistake: Striker tells Elaine to say the landing gear is down. The first exterior shot after that, the plane is shown without the landing gear down, after that it is.
Visible crew/equipment: In the beginning where the camera is following some of the characters to appear later in the film, when we see the Harii Krishna guys a cameraman and a camera on a dolly track are reflected in a shadow on them for a few seconds.