Visible crew/equipment: When Newton is playing with the robot arm and the piano you can clearly see wires attached to the top of it controlled by the puppeteers.
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: When Number 5 gets out of the truck it is no longer hanging over the edge of the cliff. It has moved inland by several feet. (00:46:45)
Visible crew/equipment: You can see a wire attached to the back of Stephanie's truck in this scene, which obviously stops it from really falling over the edge of the cliff. (00:43:20)
Revealing mistake: When Number 5 is leading Number 3 into the toilet and moves at the last minute, you see Number 5 falling over, but in the next scene, he's perfectly fine.
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?
Revealing mistake: When Frank takes the orange juice from the tray Johnny 5 is holding, the tray moves with the glass for a second. This is because the orange juice glass was glued to the tray, so Johnny wouldn't drop it. (01:05:25)
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)
Revealing mistake: After Johnny blocks the gunshots from Frank, he begins to flip a coin and imitate John Wayne. You can see the thin wire connected to the coin on the left side of it.
Continuity mistake: Johnny flicks around the radio stations and tunes into 94.1 and there is some music - he tries another station and then comes back to 94.1 and it is already into the first chorus of the "Who's Johnny?" song. (00:54:25)
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)
Visible crew/equipment: When number 5 falls off the bridge you can see a thin rope attached to him, either used to activate the parachute, or used as a guide wire to keep the robot stable while falling.
Continuity mistake: When Ben unloads Number 1 from the truck, it is almost fully erect, yet in the next shot, it is in a crouched position. (00:44:50)
Other mistake: The tree used to hold up Number 2 is very thin and weak looking, yet it supposed to be supporting a 400lb robot. Strong tree. (01:13:25)
Continuity mistake: When Ben enters the lab to call Newton for the press-presentation, the red digital clock shows 11:33:55. In the next shot from another angle of Ben, the clock shows 11:10:xx. and the very next moment it has jumped to 11:27:xx. (00:07:45)
Audio problem: When Johnny starts to make impressions of advertisements he has seen on the TV, the TV magically stops making noise throughout this scene. It comes back on when Johnny has finished speaking. (00:34:50)
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: The fence that Johnny falls against starts to break before he even touches it. (00:36:10)
Revealing mistake: Some shots used in the scene where Johnny runs from the Nova helicopter were shot using the small toy version of Johnny. There were no mountains in the area and a small version was filmed heading towards some big rocks with the camera on the ground to give the impression they were in a mountainous area. (01:30:15)
Answer: There were always 5. You see the 5 during the demonstration. Then, before the lightning hits, we see 4 of them in line, but number 5 was still attached to the generator and not in line. When they go inside, there's a weird cut that makes it look like only 3 made the turn, but if you watch closely you can see there's 4 followed by number 5.
Bishop73