Random film related pet peeve - actors who pronounce a word or name differently than everyone else in the film for no apparent reason.
Case in point- Endgame. Nebula pronounces Thanos as "Tha-Noss", while everyone else says "Than-Ose".
Other offenders:
Marlon Brando in Superman saying "Kryptin"
Roger Moore in The Spy Who Loved Me calling a character "Fek-ish", when every other character says "Fah-Kesh"
And don't even get me started on Roger Moore's pronunciation of "Saint John Smith" in A View to a Kill.