When G.O.B is first seen leaving the apartment with the alcohol, he walks in the hall uninterrupted. However, later when Buster is shown walking in the hall to the apartment, we see him pass G.O.B right as Gob is leaving with the alcohol.
When GOB is in his banana suit and gets partially dragged by the taxi, it's clearly seen that when he closes the door that no part of the suit gets caught in the door.
The change machine Buster uses at the arcade clearly indicates that it takes only $10 and $20 bills, and will dispense change in the form of one or two $10 rolls of quarters. However, it accepts Buster's $100 bill and dispenses loose quarters.
Michael is seen "dialing" a Sidekick II phone without opening it to reveal the keypad that would enable him to do so. Also, while having a conversation on it, it is actually upside-down.
In the opening scene with Michael and GOB, a crewman's leg is visible on the stairway landing.
In "Top Banana" George Sr. stresses that "there is always money in the banana stand" because he kept $250,000 in the walls of the stand until Michael burns it down. Here we find out that the local youth play a prank on the Bluth family every year by throwing the frozen banana stand into the bay. The money would not survive this.
In the first scene, once Gob moves from the Foyer into the sitting room, Michael follows and the boom mic can be soon to the left of Michael in the next shot of him.