That's strange because it only seems to be noticeable during the last half hour and it seems to be consistently way off from that point on. John how do you know this, did you read it somewhere or did you see it yourself?
From the DVDTalk forum: "As for the sync problems, as hard as it is to believe, that's the way the film has always been! It's not a problem with the DVD. This has been confirmed both by fans with previous home video releases, as well as MGM itself."
Seems like the DVD would have been a good opportunity to fix this. It seemed like the audio was consistently late or early, I don't remember which.
On the subject of Scanners, has there ever been ANY talk of doing a special edition for this film? I've avoided buying the barebones release for years in hopes of a better version.