Was watching this tonight, and there's a scene where Keanu Reeves wants to get off the bus to talk to the cops about Dennis Hopper's character. Hopper refuses at first, but Reeves convinces him to do it.

Now, on the disc, you hear Hopper say, "I want you back on there real fast!". Yet, if you watch Hopper, he CLEARLY says "I want you back you son of a bitch!".

Any idea why they dubbed it? Was it an editing error in the film itself? Or just a mistake on the disc? Or was there an actual reason for it?

Not sure. It was on the VHS like that and on the movie network like that also.

And it was like that in theaters, and was always there. Sometimes lines are changed in post production and dubbed over. It's just the way it works out sometimes