The water cooler behind Patrick appears and disappears during the early lobby scene.
Nick wears two different shirts in bed during the same night.
Nick's rolled up sleeves when he's looking for "The Joshua Tree".
In the wide shot of the bus pulling up, a man with a vest is clearly seen driving. When the bus stops, Patrick is behind the wheel.
The producers ran out of money halfway through production and nine months passed before money was raised to resume. This accounts for various actors' fluctuating weight and changing hair length, as well as seasonal changes in background foliage, etc.