Continuity mistake: At the start when DeNiro is driving the van he starts on the left side with his jacket on, then he switches to the right without it, and back again to the left with the jacket. (00:07:00)
Continuity mistake: When Norton is guiding DeNiro through the customs house with the radio from the car outside, he's in the passenger seat with the driver. When the driver pulls away to pick up DeNiro, the shot through the back window shows Norton is not in the car anymore. (00:44:00)
Continuity mistake: When Norton gets the passwords for the new cameras at the park, there are three passwords. The first and the second have three digits, but the third password has four digits. But when Norton types the three passwords, the sound was for three passwords of three digits.
Continuity mistake: The first time Marlon Brando visits Robert DeNiro at his bar, DeNiro is drinking Scotch at the table. He takes a sip, yet in the next shot, the glass is totally full. Then, he doesn't drink again, but the next time you see the glass, it is half full.
Continuity mistake: At the part where Robert De Niro is checking out the basement from below in the pipes, he sticks a tiny camera up through a grid and looks around. Later on, when they actually do the robbery, he climbs out and the grid is totally different to the one earlier on.
Continuity mistake: Near the end when Ed Norton's character changes and gets ready to leave with the gold staff, he puts the bag with the gold over his back first and then puts on his backpack. Later, when you see him running to the bus station, you see that the backpack is against his back and the bag with the gold staff is on top. This is also evident when he is talking to Robert DeNiro's character and he takes the bag with the gold off first.
Continuity mistake: Near the end of the film when the alarms are about to go off Norton points a gun at De Niro. He holds the gun with one hand, takes a step back and holds the gun with two hands, then in the next cut he's holding it with one hand again.
Continuity mistake: When the piano is being burned the scepter can be seen melting in the furnace. In all future shots the scepter is undamaged.
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.