When Slimer hands Ray his stuffed Mr. Stay Puft toy, the blue trim on the doll's head turns white between shots.
When the Ghostbusters arrive at the Pallo Mansion and exit Ecto-1, Winston is colored as Ray. As he starts to move, he changes into the correct colors, first his face and then his uniform.
Near the end, when Winston says "But you were just too quick on the draw", his skin is colored incorrectly.
Twice, when Ray is wearing the pink bunny suit, he reaches down to pick up items from the floor and his sleeves are shown to be the color of his Ghostbusters uniform. The first time as he picks up his proton pack, the second time is when he reaches for the book of spells.
Winston says the balloon shaped like Ray has been moved to the back of the parade, yet it passes them before the new Grand Marshal's float does.
When Ray hands Winston his proton pack and says they should take it and use it for parts, Ray's lips aren't moving when he says that.
Ray says that Morrisville is only 30 miles away from NYC when in reality it is at least 200 miles away.