Continuity mistake: At the beginning, when the NASA spacecraft lands on the MAC planet, there are three silver antenne around the side of the craft which are absent in some shots. (00:02:15)
Revealing mistake: When Mac is escaping down the hill in the yellow toy car, the image is reversed - the "KC" lights are mirrored. (00:51:00)
Revealing mistake: Supposedly Mac makes the unplugged TV work with his energy, and Eric looks at it in awe and inspects its loose cables. But if you look at the right side of the TV, you'll see there's another black cable coming out of it hidden among the cardboard boxes, which makes the whole trick work.
Continuity mistake: When Mike is getting ready to pick up Eric and haul him into the van as they flee from the cops, in exterior shots Debbie is leaning out of the window, but in interior shots of the van, she is sitting inside, and the van window is closed as well. (01:07:20)
Audio problem: When Eric is riding through the shopping centre, away from the cops, his mum is riding the escalator when she hears him. She then says "Excuse me, I'll be right back," but her mouth says something else. (01:06:40)
Audio problem: When Eric's wheelchair goes out of control, and he starts to roll down the hill, Debbie cries out "Eric" but her mouth doesn't move. (00:32:35)
Revealing mistake: After Debbie and Eric have captured MAC in the vacuum, it goes out of control, causing Debbie to get flung around the room. The track that goes up the wall, across the ceiling, down the other wall and across the floor is visible for this stunt. (00:42:20)
Continuity mistake: When Eric first talks to Debbie, as she stands on the balcony, the position of the bracelets on Debbie's right wrist keeps changing. (00:23:35)
Continuity mistake: During the dance at McDonalds tables and chairs suddenly disappear from the place and are replaced by dancers.
Revealing mistake: When Eric and Debbie enter McDonalds, they go to a table and then Courtney comes over and gives them a drink each, however it is clear that the cups are empty, as they are clear and move around lightly and make hollow sounding noises. (01:01:00)
Continuity mistake: When the MACs' are sucked into the NASA spacecraft, an explosion occurs, causing a grey cylinder capsule to fly off. In the next shot the capsule is attached to the craft again. (00:04:25)
Continuity mistake: When Eric is playing with his remote control car, he stops and takes the battery out. In the next shot, when MAC touches the car, the car is now in a different position. (00:20:00)
Continuity mistake: In the panning shot of the NASA lab, the clock's minute hand can be seen on the half hour mark, yet in the close-up of the Professor, the time reads eight twenty. (00:06:50)
Revealing mistake: When Eric falls off the cliff and into the water, you can see in the overhead shot that Eric is a dummy.
Continuity mistake: When Eric is about to wake up from his coma his jacket swaps from very open to slightly open between shots.
Revealing mistake: After the vacuum cleaner scene, Eric tilts the Coke can completely to give some to Mac but no liquid falls out, revealing it's empty.
Continuity mistake: When Eric wakes up and follows the remote controlled car his hair is messy but in a close-up it's perfectly brushed.
Revealing mistake: Wires lowering the alien spaceship are perfectly visible. In the following close-up they're gone.
Visible crew/equipment: At the very end, the camera crew is visible reflected in the side of the car.
Revealing mistake: When the huge explosion happens, it is blatantly obvious that Eric and his wheelchair are superimposed in the shot. When the main scene shakes a bit, the superimposed wheelchair does not move. This same explosion minus Eric and his wheelchair appears in an alternate ending. It's the same exact shot.
