The only thing you could call this is a slip-up, although to me it seems more like certain people thinking the film was getting so silly that anything went.

When the Sheriff is storming off to bed in a rage, he shouts to one of the girls "You, be in my chamber at ten o'clock!". He then turns to another girl and says "And you, at quarter past!". Since the clock was not invented in England until 1386, and the minute hand didn't show up until 1660, these girls must have been astonishingly good at counting seconds !