When Joe enters an elevator on first floor not the same elevator Operator when he leaves the elevator.
At the Alcoholics Anonymous meeting, both Jim and Joe say their full names; last names are usually not used in AA meetings, which is how people remain "anonymous".
When Joe enters the sleazy motel room where his wife is having a bender, he presses the lower button on the old fashioned button type light switch to turn the light on. In fact, the electrical code called for the upper button to always be the ON button.
When Joe is in the hospital for the first time, a doctor and two orderlies come and check up on him from the fenced window of his cell door. In the next shot, the only shadow that is cast on Joe is that of the fenced window, not of the three men looking at him from the window.
In Kirsten and Joe's closeup on the street outside of her office a shadow of the complete microphone unit, and boom arm, are visible for several seconds on the overcoat of a passerby coming up behind them.