The cane that Amos Flint is carrying disappears completely when he turns into a gorilla.
Because the Stooges' reaction to Mr. Flint's transformation was reused footage from "All Gummed Up", they all look to the floor in awe. But in "Bubble Trouble", Amos isn't shrinking. They have no reason to look down.
When the transformed Mr. Flint is "twisting" Moe's foot, we view Moe's reaction, his pain-stricken face. We hear "ah's" and "ow's" in the soundtrack, but for the majority of the shot, Moe's mouth shapes an "ah" and we never see an "ow", except for the last second, and even then the soundtrack doesn't quite match.