Revealing mistake: When Phil drives the truck off the cliff, you can see right through the grill of the truck (meaning there is no radiator or engine), and the transmission is also missing, as you can see when the truck is falling upside down. Without an engine or transmission it would be hard to drive off a cliff.
Revealing mistake: When Phil escapes the police with his drunk friends in the car, their stunt doubles' different faces are visible as they start driving on the tracks.
Revealing mistake: When the truck goes over the quarry, it's empty.
Answer: Old fashioned hotels have a single boiler for all the hotel rooms. Once the hot water reservoir is used up there won't be any more to use until the reservoir is refilled. This only happens once every few days.
lionhead