When Shawn is being forced, by Jacqueline, to attempt to open the vault, he says "Levers, why did it have to be levers?" This is a parody of the famous line said by 'Indiana Jones' in "Raiders of the Lost Ark": "Snakes, why did it have to be snakes?"
The trivia items below may give away important plot points.
Despereaux, after revealing that he had faked his death, mentions the conundrum of having to prove he was dead, and that "It would be impossible to leave a large enough sample without losing a hand or a body part." Cary Elwes, the actor that portrays Despereaux, starred in the first and final 'Saw' movies, and his character was forced to cut off his foot in order to escape a room in the first 'Saw.'
The GPS tracking unit that Cary Elwes used to find the warehouse is a military GPS device called PLGR (Precision lightweight GPS receiver), pronounced "plugger." It was used extensively in the first Gulf War and is by no means "light." It's military nomenclature is the PRC68, pronounced "prick sixty eight."