Corrected entry: Whilst Brantley is getting changed in his new office, Jean his new secretary comes and surprises him. If you look closely at the door that she opens, you can see duct tape holding the door latch open. (00:44:15 - 00:44:45)
Corrected entry: When Michael's character gets on the escalator, his tie length is below his belt. As he gets off the escalator, it's way above his belt.
Correction: The scene you're talking about is different days. It's a montage of him going to different offices. In the first scene his tie is blue and in the next one it's red, showing he's changed.
Corrected entry: When Michael J. Fox copies his face to give to his "Uncle", he clearly has one hand outside the copy machine, but when he hands over the copy, both hands are on the image.
Correction: He puts his second hand inside the machine in time for it to print properly after pressing the print button.
Corrected entry: When Michael J. Fox arrives at Auntie Vera's house and she is trying to seduce him, she gives him a whisky and he throws it away leaving an empty glass. Next scene the glass is half full again.
Correction: Actually Auntie Vera hands her drink to him & says "have another".
Corrected entry: In one shot, the boss chases "Whitfield" out of the conference room so he could finally see who he is. In the very next shot, "Whitfield" is sitting in his office late after hours. Why didn't the boss just go to Whitfield's office?
Correction: Every time the boss goes to his office, Whitfield is nowhere to be found. The boss chases him because he finally finds him in person at the meeting. He had no way of knowing Whitfield would be working late, and surely Whitfield would have made sure certain people were gone for the night before going to his office. The whole premise of the movie revolves around the joke that he can "be there without being there" and still produce results.
Corrected entry: In the where Brantley and Vera are in the pool house after their swim, Brantley states "I'm going to make it to the top by myself". However, the next day in his future office, he reminisces back on that moment and remembers himself saying, "I'm going to make it to the top on my own".
Correction: This is a character mistake, misremembering the event, not an error in the movie.
Correction: The tape isn't over the door latch but above it over where a deadbolt would be. Not an uncommon thing and not a mistake.