9. Ariadne's Hair Bun
This is a detail you probably didn't think too much about, but there's a reason why Ariadne wears her hair in a bun during the hotel dream.
Since the characters would be floating during this sequence, her hair was in a bun so that the filmmakers wouldn't have to figure out how her hair would flow around in zero gravity.
This might seem lazy, but if you made a movie that required such a heavy amount of special effects (most of which were practical), would figuring out how hair works in zero gravity be a priority concern when you could avoid it entirely?
It was a simple solution to a minor problem the filmmakers didn't have or want to deal with. There was so much work that had to be put into this movie, it only made sense to cut corners this minor.