When Otis Driftwood is sitting on top of the steamer trunk being pushed by the porter and has the porter stop in front of Rosa's cabin so he can go inside, he's wearing a hat. In the next shot, from inside Rosa's room as he enters it, he's not wearing a hat. When he leaves Rosa's room and goes to Mrs. Claypool's room he's still not wearing a hat, but after he leaves Mrs. Claypool's room and we cut to the next scene which is Driftwood entering his stateroom, he's wearing a hat again.