Peter Teschner tells TMZ ... there were several screenings of the historical drama during the editing process ... but he doesn't remember a screening where music was missing. According to Peter, they always had music in the film for screenings ... including original songs by Pharrell Williams, as well as a temp score.

This directly contradicts Glen's claim, which he made on the "Therapuss with Jake Shane" podcast a couple weeks ago.

Remember, the actor said he threw up after watching a rough cut of the movie without special effects or music ... saying he feared he had ruined the movie with his performance.

While Peter says it's entirely likely Glen freaked out about his performance, he doesn't recall a single instance where a screening was THAT rough.

He also doesn't agree with Glen's point that effects added later on made the movie a lot better. Per Peter, Glen's rough cut scenes versus his final cut scenes weren't changed much at all ... stating the actor's performance was great.

The movie came out almost 8 years ago ... so, perhaps Glen is misremembering how things went down???