Visible crew/equipment: When Number 5 plays with the light switches on the way to the disarming section, a coffee serving robot comes through the corridor, and the reflection of the camera is visible in the coffee pot. (00:12:15)
Visible crew/equipment: When we see a wide shot of Stephanie's truck driving through the town, look closely to the left of Johnny when we see the truck start to go up the hill. You can see one of the puppeteers hiding beside the robot. (00:21:35)
Visible crew/equipment: Look REALLY closely at the mirror in the background when Stephanie is trying to control Number 5 from destroying her house. You can see a man leaning over in its reflection. Possibly the director or other crew member. (00:32:15)
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)
Continuity mistake: The scene where Johnny falls off the bridge, opens his parachute and lands in Stephanie's truck is obviously fake. Johnny doesn't move, yet all the backgrounds do - the scene was obviously filmed infront of a blue screen. (00:20:55)
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)
Visible crew/equipment: When Johnny is blocking Frank's gunshots with pieces of Frank's car, you can see the wires attached to Johnny's arms for the puppeteers to control him. In the last one, you can even see one of the puppeteers' hands. (01:06:25 - 01:12:21)
Continuity mistake: When Johnny is exploring Stephanie's house we see 3 shelves in the background and on the middle shelf is a grey cat. In the next shot there is a black and white cat in its place. (00:30:50)
Continuity mistake: When Stephanie runs to the shelf to pick the second volume of the encyclopedia the amount of cats increases/decreases randomly between shots. Also, the amount of books and their position changes.
Other mistake: During the shot where Newton and Stephanie first argue ("did you say the the robot drove the truck?") in the background Number 1 is missing its treads, leaving the idler wheels and internal chassis of the robot's tread mechanism exposed. (00:45:05)
Continuity mistake: As Johnny runs from the Nova helicopter his chest plate falls down, in the next scene, it's back up again. (01:31:05)
Continuity mistake: When Johnny 5 is being pushed out of the building by the motorised bin, his mouth guard is off. But later when he is in the truck it is back on, only to come off again after he falls off the truck. (00:12:55)
Other mistake: When Johnny is changing his arm in the back of the Nova truck, it's quite obvious that the new arm he 'attaches' isn't realy attached at all. (00:51:50)
Continuity mistake: The robot hand in Newton's lab is supposed to be playing the keyboard, but most of the time its fingers aren't even touching the keys at all. (00:08:15)
Continuity mistake: When Stephanie and Mrs. Sapeeto are talking after Frank leaves, we can see Stephanie's truck in the background with no Johnny 5 on top of it. (00:24:00)
Continuity mistake: Crosby's tie was open after the jacket was on, then crossed as he says "but just one dance"
Continuity mistake: Number 5 goes to the kitchen and the position of the skunk and the stuff on the counter changes between shots.
Continuity mistake: When Stephanie shows her ants and rabbits to Number 5, the amount of cats on the shelf behind suddenly increases between shots.
Continuity mistake: Ben brings a jacket to Newton, who looks at him. A shot later he is looking at the opposite way.
Continuity mistake: During Frank's second visit to Stephanie's home the stack of pancakes J5 is holding decreases from a load to a few over several shots. (01:04:50 - 01:05:20)
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