Comment by iaaan
2 hours ago
There's a famous example of this in Malcolm in the Middle where the camera cuts to a different shot and a stand-in for Dewey is visible in the 16:9 release, but was not visible in the original 4:3 broadcast. So in one shot you have Dewey's normal actor, then in the next there is some random kid.
A recent similar example was Mad Men rerelease in 4k where the VFX weren't redone properly after a rescan of the film and you can see the man operating the machine with the pipe that spews sick out of a characters mouth.