The ring that Brad Pitt wore on his right hand in the film was a gift from ex-wife Jennifer Aniston. He wore it in the film as a way of paying homage to her.
The "TeenBeats" Rusty is teaching to play poker go uncredited. They are Joshua Jackson (best known as Pacey in "Dawson's Creek," a TV teen drama), Holly Marie-Combs (best known as Piper in "Charmed," a TV drama), Shane West (best known as Landon in "A Walk to Remember," a film), Barry Watson (best known as Matt in "Seventh Heaven," another TV drama) and Topher Grace (best known as Eric on "That 70's Show," a TV comedy).
Rusty Ryan is eating in nearly every scene he is in - on the DVD, there is a commentary by Brad Pitt (Rusty), where he says that during filming, he realized that since his character is so busy, he would have to eat whenever he got a chance, so he and the director decided to have him eating in every scene.
When Saul (posing as Mr. Zerga) collects his briefcase/package one of the "bodyguards" says "ya vas lublu." This is also said in "The Great Escape" (1963) as the only piece of Russian that Danny (Charles Bronson) knows, he translates it as meaning "I love you."
The two restaurant scenes where Danny and Tess exchange words were filmed at Picasso restaurant at the Bellagio.
In the scene where the crew is mingling around the pool at Rueben's house, "Clair de Lune" can be heard playing in the background. This is the same song that was playing at the end when the crew was standing at the railing watching the Bellagio water show.