Other mistake: When the kids are standing on the balcony after escaping from the dungeon, the arena is shown in the distance. Jimmy asks Goddard to activate his binoscope to get a look at their parents in the arena. The problem is that the walls of the arena obscure the center where the parents are dancing, which means that Goddard wouldn't have been able to get a clear view without going to a higher level. (01:04:55)
Other mistake: The size of the town Jimmy lives in is inconsistent with the size of the population shown. The town is quite big if it has its own mall, amusement park, and a large elementary school. Yet combined with the kids and adults seen, there couldn't be more than a hundred people living in this town.
Answer: This is not meant to be a realistic film.
BaconIsMyBFF