When Gopher and Buddy are speaking in the lobby, an extra in a brown leather jacket can be seen climbing the stairs behind Buddy. The next moment, that same extra can be seen walking in back of Gopher and Buddy on his way to the stairs.
When Benny (Sonny Bono) first spots the envelope that fell out of the jacket, it's clearly in the middle of the floor. But when he leans down to pick it up, it's right next to the bed.