time: 29:20, it happens REALLY fast, so get zoom and pause ready on your remote.
where: twin pine mall
as the doc has his hands up and awaits being shot by the libyans, he tosses the gone. in that split-second shot, WAAAAAAY in the background are either two people, or one person and his/her shadow, walking right through the shot in front of a red dumpster.
now, if one wanted to romanticize this slip-up, you might say it's secretly an inserted shot of marty coming back from 1955, but for obvious reasons, it's not. first off, marty arrives much farther to the right of the dumpster, at the lone pine mall clock. secondly, the people (i really think there are two) are casually strolling in the opposite direction.
still very spooky stuff though.
dvd of the movie... on a good lcd tv if possible.