was there any significance in the bloody sleve thing at the end?
Yes.
Of course, what we learn is that Sydney had killed John's father in Atlantic City. He ended up leaving that in his past and until he ran into John outside the diner... the issue never came back into his life.
The blood on his sleeve, of course, was there because he killed the man in the hotel room that owed Clementine money. By looking down on it, he realized what a terrible thing he had done... but just like John's father... he covered it up, and moved on.
I think it was a nice twist to the end of the film. The entire point of the movie, was MOVING ON. A more dubbed-down idea imposed in "Magnolia".
Don't get me wrong... this movie is no Boogie Nights, no Magnolia... and no Punch Drunk Love. It was a good independent film... and most noteably, a great story backed up by a pretty darn good cast for a low-budget film.
For his first film... you saw a lot of potiental in PTA's future.