I recently had a friend over with limited English skills and fairly picky taste in movies, so we settled on a big, broad comedy with lots of physical humor: Ace Ventura: Pet Detective. I remembered finding this hilarious as a kid and I thought it held up fairly well with the obvious YMMV on Carrey's mugging, but I was kind of shocked at just how much the finale revolves around one extended gay panic joke. Like, that's the entirety of the finale. He kissed a pre-op transgendered woman, so everyone literally pukes. My friend was totally unfazed (LGBTQ issues are pretty low-visibility in China) but I was kind of bummed. Not in a "destroy every copy" kind of way, but in the sense that something I whole-heartedly enjoyed as a kid now has an uncomfortable asterisk that means I probably won't be in a big hurry to revisit it any time soon.
I think Breakfast at Tiffany's is probably the gold standard for classic movie with the really unfortunate part you have to accept in context (I've actually never seen it), but I'm curious as to whether anyone else has a personal example of a movie that's made them uncomfortable on a re-watch because of a particular aspect that doesn't sit well now.