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)
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)
Answer: Driving from Central Oregon to Montana only takes about 12 hours. They could drop off Number 5 and be back to move Stephanie and Newton out of their houses within a day or two.
LorgSkyegon