Corrected entry: The volume of Jo and Bill's voices changes in the scene where he tries to stop picking up the Dorothy sensors that a tornado has already destroyed. When they're in the truck, they're loud probably because their dialogue was recorded in a studio later. When they're outside their voices aren't as loud because they were in the location.
TedStixon
9th Sep 2020
Twister (1996)
Correction: People's voices changing volume isn't really a mistake because it can easily just be that they stopped speaking as loudly for any reason.
Correction: It's common in movies for audio - especially dialogue - to be boosted or lowered depending on the needs of the scene. (Ex. In this case, the voice-over audio being boosted while they're in the car so the audience can hear them when they wouldn't otherwise be able to - we're basically hearing the conversation in the car from outside.) A filmmaking tactic such as this can't really be counted as a mistake because it's a common and necessary requirement in filmmaking in order to convey the dialogue, and is used countless times in just about every film. Nothing about it is technically a "mistake" per se.
TedStixon