(OK, I know that strictly speaking this is a game slipup, not a movie slipup. But since the only other game slipup I've seen --

http://www.slipups.com/items/31199.html -- (for Grand Theft Auto: San Andreas) is also under Movies, and there isn't a separate Games section, I've followed that lead.)

Play the final level of Episode 1 (L.A. Meltdown), the level entitled "The Abyss". (If you're impatient, use the cheat code "dnscotty105" to go directly there.)

At one point, Duke encounters a plaque rising out of the ground, saying "SAN ANDREAS FAULT" plus plenty of other writing which is too small to read. As he approaches this plaque, an earthquake occurs (drastically reshaping the terrain) and Duke says "Holy Sh**!", obviously in response to the quake. The trouble is, he says it just before the quake hits!

(Clearly an error in the script which runs the level. It's very noticeable.)