When Laurel and Hardy are returned to their wives by the police officer, as they are led inside the house, the camera tilts back slightly and the boom mic is visible at the top of the frame as they walk toward the couch.
At the beginning of the film when Stan and Ollie return home from their lodge meeting, and there's confusion over which house Stan is in, the light in Stan's house (visible through the glass panel in the door) keeps changing from off to on and back again.
In the first wide shot in the ship docking area, before Laurel and Hardy's wives arrive, following news of the Honolulu ship sinking, a crew member and camera tripod are clearly visible reflected in a glass door.
When Lottie runs into the house to answer the phone, the camera tilts up just a bit too high, revealing the beams, wires, and mechanics of the studio ceiling at the top of the frame for a brief second.
When Laurel and Hardy are in the back of the cab on the way home, every time Hardy leans in to talk to Laurel, his shadow falls across the rear-screen projection of the traffic seen through the back "window" of the cab.