After she's tried to seduce Brian, Sally brings her record player into his room and plays a record....this is the 1930s so the record should be spinning at 78rpm. But it isn't...it's clearly playing at 33.
As Max drops off Brian and Sally packs for the African trip, Brian's shirt changes style and colour. In Max's car his shirt is blue with a rounded collar but, by the time he enters the apartment, it is white with a pointed collar.
Brian is seen pushing a bicycle while walking with Sally. The front light on the bicycle points downwards. Later, Brian and Sally join two friends for a cycle ride. Brian rides the same bicycle with the downward pointing light. In the same scene, when the four are pushing their bicycles and eating ice creams, Brian is pushing a bicycle that doesn't have the downward-pointing light.
The subtitles are inconsistent with how they show German speech/singing. During the opening, with the Master of Ceremonies (MC) singing in different languages, the subtitles show the German words in German. In at least one other part of the movie (when he's singing/dancing with the ape), some German words are translated into English in the subtitles. In this same ape scene, it may seem to non-German speakers or to viewers with no knowledge of what spoken German actually sounds like, that the MC is inconsistent with his pronunciation of English words that start with 'W'. Sometimes he pronounces them as if they start with a 'W', sometimes with a 'V' (for example, the German "Willkommen" (English "welcome") may appear to an English speaker as if it should be pronounced with a "w" sound, but a native German speaker will, in fact, pronounce it as if it started with an English "v" sound (villkommen).