Winston's last name is misspelled "Zedmore" in the Ghostmaster's book.
When Winston shouts "Bullseye" and is about to stomp on the Ghost Trap pedal, it's button is layered behind the pedal instead of on top of it (animation cel layering mistake)
After Animax is trapped, when Peter says "In the old days the ghost didn't come barging into headquarters", Winston is standing in the foreground. As he turns his head, and moves his arm, several animation layers are superimposed over each other, making his features look blurry.