Revealing mistake: When John Cusack is driving the actress, there is a shot looking over his right shoulder at the dashboard. The speedometer reads 0 mph. (00:08:15)
Revealing mistake: When the guests open up the freezer containing the dead hotel clerk, it falls towards the camera, i.e. the viewer. Right before it changes to the reaction shot of all the guests, the corpse blinks. (00:52:50)
Revealing mistake: When the woman Ed hit dies, her eyes move. (01:00:30)
Revealing mistake: When John Cusack notices Timmy's mom is dead, you can see her still breathing. (01:01:35)

Revealing mistake: Near the end of the film when we see Rhodes shoot Larry in the chest, you can see an outline of something underneath his vest, very obviously a device/squib simulating being shot in the chest. (01:15:15)
Revealing mistake: When Ed is driving the limo at the beginning of the movie, the gearshift is in the park position.
Revealing mistake: When John Cusack is coming out of the motel grounds looking for Jake Busey, the gate is banging away furiously from the wind but the rain is coming straight down. The rain should be sideways if the gate is banging so much from the wind.
Answer: The motel isn't real, and neither are any of the characters in its proximity. They are all aspects of Malcolm's personalities that are being killed off one by one in order to make sure his true murderous personality is vanquished. As such, the session by which Malcolm is being forced to do all this is designed so that all the personalities are stuck within the same place with no chance of leaving, which explains the bad storm, the road obstruction, etc.
Phaneron ★