Revealing mistake: In the scene near the beginning it shows a big guy converting a 7-10 split and celebrating. If you watch it closely you will realise that the 7 pin is lined up too far to the left and the ball is already in the gutter when it hits the pin. The movie makers could have at least bothered to repaint the pin placement lane markings so it would not be so obvious that the pin had been moved.
The Big Lebowski (1998)
1 revealing mistake - chronological order
Directed by: Joel Coen
Starring: John Goodman, Julianne Moore, Jeff Bridges, Steve Buscemi, Philip Seymour Hoffman, John Turturro, Tara Reid, Peter Stormare
Continuity mistake: When the Dude is in Jackie Treehorn's estate, he pencils over a pad of paper to see what Jackie wrote down while he was on the phone. He then hurriedly crumples up the piece of paper and shoves it in his wallet. Then, when we see the Chief of Police of Malibu looking through the contents of The Dude's wallet, the paper is there, neatly folded in fourths.
Goon: What the fuck is this?
[Picks up a bowling ball hesitatingly.]
The Dude: Obviously you're not a golfer.
Trivia: This isn't really a mistake, just something to note - throughout the whole movie the Dude is not seen bowling once. Also, every time you see Donnie (Steve Buscemi) bowl, he gets a strike, except for the last bowling scene, he does not get a strike, and he dies of a heart attack a few minutes after this.
Question: What role does Paris Themmen play in this movie? (IMDB.com only lists him as "uncredited".).
Answer: Themmen plays a background bowler in pretty much all of the bowling scenes. I don't know if this is necessarily worth a credit, but I guess his agent disagrees with me.