Am sure most of you know, but for those who don't... every film unit has a continuity boy, who keeps tab on the costumes and props on the sets and maps the same with shooting schedules and the script. See, his job is to ensure over a one week schedule of shooting a single scene that possibly amounts to about 10 minutes onscreen, that the characters are wearing the same attire and the props have the same stuff kept at the same place for a week. Now, the continuity boy is only human and errors do happen. Some of these errors are glaring onscreen and somehow escape the editor's scissors (he's human too, you see). And thus the bloopers. You see the hero wearing blue shoes before he enters a house and when he comes out, hey presto! The shoes've become white! Or a forehead gash suddenly decides to switch places from right to left or in some cases make a hasty exit from the forehead. When I was a kid, I wouldn't notice these things a lot. Then one day, I did. I was watching this highly emotional scene of a dying hero in his mother's lap, his left hand bloody with a bullet wound. The next moment I see the same wound on his right hand. I blinked. Twice. But the wound remained in his right hand. It was interesting and funny. Then I made it a point to keep my eyes open for such bloopers and boy, movie watching was not the same anymore. On an average, every two movies out of the ten I watched were agog with such 'continuity' errors. You might see these documented in some film magazines as well. Filmfare had a column 'reader's don't digest' on similar lines.
Hmmm, this was just as rantish as it could get. *Sigh*