In the last third of the movie, Ricky has a scab on his forehead. Sometimes it's over his left eye and sometimes it's almost in the center of his forehead.
When Bobby, Ricky, Horrace and Ruiz make contact with The Welshman in the nightclub, a very conspicuous female extra wearing a tight sky blue sweater and a black bandana is visible behind the Welshman and the others (i.e. she appears to be on both sides of the club).
When Ricky and Bobby are in the plane and Ricky is talking to Terri the flight attendant, his champagne glass is empty/full/empty between shots.
During the ceramic painting scene Ricky says ".... if we play this right....." he is holding his hands together the camera angle changes and he is holding a paintbrush in his right hand.
In the painting scene, during the "isn't it fun to paint" exchange between Vaughn and the little girl, Vaughn has partially painted the ashtray; in the next shot, the ashtray is unpainted and no paint is on the table; in the following shot it is partially painted again.
During the scene at the zoo by the aquarium.
After around 38 minutes, when Bobby and Ricky are in "The Cupping Room", a flashing red camera light is visible on Bobby's right leg before the camera pulls away.
At the end, when Bobby is kneeling down talking to Chloe, a boom mic is visible in the mirror behind him, especially when he stands up again.
Ricky says that Strega is a digestif, but both Ruiz and the Waiter correct him, saying it is an apertif. Strega is indeed a digestif.