At the end of the film the words "STAFF ONLY" painted on the glass door are painted on the wrong side of the glass. It reads "STAFF ONLY" on the staff only side of the door but reads reversed from the public side of the door.
There are people in the main office waiting to see an outfit modelled. Mary (Patricia Dainton) comes in from the door marked Staff Only to model the clothes, so the door is not wrongly marked, it is marked as Staff Only from the main office because that is where the staff come from to enter the main office.
When we first see the Italian music group one of the musicians is holding a banjo mandolin; an instrument completely unknown in Italy and certainly not heard on the soundtrack. When they next appear at the dance, one musician has a correct bowl-back mandolin but is clearly not playing the music on the soundtrack.