As Luke is running away from the disarmed (sorry for the pun) wampa, we hear his lightsaber power off, yet the glowing blade is still visible. This occurs in every clip of the scene I've looked at, including the iTunes HD version, which is identical to the 2011 Blu-ray releases. (Not including fan edits) And it's documented on IMDb.
I noticed this mistake the very first time I watched the movie, and it continues to stick out to me like a sore thumb. With a mistake this obvious, how come it hasn't been fixed over the multiple re-releases since the original? Has it been left in on purpose for some reason?