The amount of beer and foam in the two glasses Algy has on the tray he brings to the room changes between shots.
The players in the opening credits are set out in the form of a theatre programme. However, notwithstanding the film takes place in England, the spelling on the programme is the American 'program'.
However, while the film is portrayed as taking place in England, it was produced in the U.S.; thus, the Americanized spelling of "program" in the credits is not inconsistent.
As this is his first adventure, Captain Hugh Drummond is not yet infamous for his escapades. So how did Dr. Lakington know Drummond by name and rank upon meeting him for the first time? And how did Irma know that Hugh's nickname was Bulldog? Nobody else had used that name previously in the film's dialog.