When Bud and Lou are ice fishing, an off-camera seal barks and Costello adlibs: "Somebody got a car up here, driving?" The film is set in the 1890s, before the automotive era.
When George (Lou Costello) comments that Nugget Joe (Tom Ewell) has quite a list of enemies, he says that there are twelve names on the list. If you count up the names in the notebook, there are only eleven on it.