When Stan and Ollie are escaping from the bedroom, the rug is already halfway out of the window in the outside shot. When we see Ollie finally fall from inside the room, the whole rug is still inside.
During the runaway bus scene, the double-decker goes past the same buildings twice.
Although the sign outside the building reads "Arthur Hurry's School of Dance: Laurel and Hardy Proprietors" on the outside, inside the door says "Laurel & Hardy's School of Dance."
When Stan discovers the secret bar, he first places the book on the bar with the spine facing outwards. When the bar reappears a minute later, the spine is facing towards the wall.
During Laurel's dusting scene, an off-camera female voice (probably Trudy Marshall's) can be heard laughing.
When the bricks begin to rhythmically hit Hardy on the head, the sound effect can be heard prior to the bricks making contact.