Blade (1998)

Audio problem: Right before Blade throws his sword to retrieve his EDTA in the final battle, he leaps to his feet as Frost attempts to stomp downwards on him. As Frost's foot his the concrete ground (or Blade's shoe, as it's unclear from the shot as the impact is out-of-frame), the audio features an incredibly loud and out-of-place flesh-on-flesh punching sound effect, instead of a proper "shoe stomping concrete floor/Blade's boot" sound that should have been played.

Audio problem: Just after Quinn has been nailed to the wall at the beginning of the movie, he makes some strange noises and then starts talking in "vampire language." This has obviously been dubbed in post-production.