Continuity mistake: In the start of the movie, depending on the scene, the words on the bus change between "schoolbus" and "school bus".
Continuity mistake: After Schneider is tied to the showers he is stripped and we see him being smacked with towels across his bare butt. When the last towel hits him there is shot of him writhing in pain and he's still wearing the black leather pants he had on earlier.
Continuity mistake: When the two boys are told to assume the position, the amount of grass on their tops changes between camera angles.
Answer: I think the coach's death was a play on his character being at a S&M bar. People who frequent those places are usually into bondage and being dominated. Hence being tied up, and whipped with the towel. It also fits in with the homoerotic subtext throughout the movie.