Other mistake: When Brando, Norton and DeNiro are at the table, DeNiro accepts the job and tells Norton the stipulations. When they first begin talking the ashtray on the table is empty, but when Norton is telling his story there is a book of matches in the ashtray, then later they are gone again. Notice, none of the three characters smokes.
The Score (2001)
1 other mistake
Directed by: Frank Oz
Starring: Robert De Niro, Edward Norton, Angela Bassett, Marlon Brando
Plot hole: When the security guards enter the cage housing the blown safe there are no traces of the water used to break the safe - not even on the (dry) floor. This happens only minutes after the explosion sent the safe door and gallons of water across the cage.
Trivia: Most of the conversations between Robert De Niro and Marlon Brando are improvised.
Answer: He didn't know for a fact that it would happen, but he was experienced enough in these kind of high-stakes operations to plan for literally every contingency, including a double-cross.