Continuity mistake: When Johnny 5 nearly drives the snack wagon over the edge to where it is hanging, it appears to have miraculously moved right back from the edge, making it look like he never went nearly over in the first place.
Continuity mistake: Number 5 picks up mud and throws it at number 1's face. But from there on, Number 5's hands have no mud on them. We never see Number 5 clean his hands, so were did the mud go?
Continuity mistake: The amount of mud on number 1's face changes to nearly nothing to loads.
Continuity mistake: Just after Stephanie's truck stops on the cliff edge, she gets out and goes to talk to Ben and Newton who were following her in their Nova truck. She goes around the back to talk to Ben, and sees him taking Number 1 out. In the first shot of here her arms are by her sides, but when the view cuts to a different angle, she has her right hang on the side of the van door. (00:45:25)
Continuity mistake: When Johnny gets scared of Stephanie's dog, he moves backwards and falls off the porch onto the ground below. His actual framework stays in the same position, but the tracks he uses to move around are strangely upside down. The tracks are made up of long black rectangles with curved edges on the top, but when we see Johnny lying down, the shaved corners are at the bottom. (00:36:15)
Continuity mistake: In one of the first scenes where the robots are being tested on the fake tanks and trucks, you see the robots' lasers being raised from the front. The front of the lasers come up into firing position as opposed to lowering into position. This is not possible considering the lasers are mounted on their backs and the front of the lasers lower into firing position in the rest of the movie. (00:03:05)
Continuity mistake: Just before we see Johnny fall off the bridge we see a shot of him speeding past some roadblocks. Look at the size of Johnny compared to the roadblocks. They are practically bigger then him. This was obviously a small replica robot filmed with the camera on the ground, to give off the impression it was the real thing. (00:20:45)