What's the worst part of an otherwise perfect film?

In my opinion, 'Alien' is a very almost perfect movie. Performance, Narrative and direction wise, it's basically sublime. But one scene in it (the ending escape pod scene) really bugs me. When the Xenomorph is clinging to the outside of the ship it looks a tad goofy. Almost comparable to a power rangers villain. The film does an amazing job with keeping the creature mysterious and in shadows making the audience fill in the blanks with their imagination much akin to Bruce the Shark in 'Jaws' but in that one scene it just looks poor in my opinion. What are your opinions on otherwise perfect films with one issue that bugs you?EDIT: Spelling. via /r/movies https://ift.tt/wPNHVtK