Factual error: In the scene where the fire department responds to the fire, the engine is 42. Yet all the fireman's hats say 6. The engine company, station etc. would all be the same number so their helmets should have also been 42.
Factual error: In the scene where the prison van crashes and flips, the prisoners grab the keys and get out. Even if they did obtain the keys, they wouldn't have been able to unlock the locks on a prison vehicle from the inside.
Factual error: Throughout the movie, scenes show orange groves and rolling hills, but neither exist within hundreds of miles of the real Happy, which is located on the semi-arid plains of the Texas panhandle.