All spoilers will be unmarked ahead. Read on or go back — make your choice.

There's at least one reveal per Saw film.

Saw:

Zep isn't Jigsaw; the man lying on the ground in the bathroom isn't dead, and he is Jigsaw.

The events in the house are not taking place at the same time that the cops are watching it.
Amanda is actually an accomplice of Jigsaw.

Lynn and Jeff are married, and Jigsaw kept this information from Amanda to test her.
Jigsaw is responsible for the loss of Jeff's other child, locking her away in a location that only he and his accomplices knows.

The film's events take place at the same time as the events of the previous film.
Hoffman is another apprentice of Jigsaw.

Jigsaw recruited Hoffman after Hoffman killed his sister's murderer with an inescapable trap.
The point of the main game was teamwork, and all five victims could've gotten out alive if they hadn't turned on each other.
- In the first room, the keys are all identical and they simply could've handed them to one another to unlock their collars.
- In the second, the tunnels are big enough to hold two people (this one's especially idiotic, considering they didn't even bother to look in them first, instead instantly fighting for the keys to the locks).
- Third, all they had to do was touch the electrodes all at once and get a minor shock to open the door.
- Finally, had all participants survived to the last room, they would've had to give only two pints of blood each in the machine to pass the game.

Hoffman and Amanda both knew of each other's work as Jigsaw's apprentices; Amanda killed Lynn in the third film because she was being blackmailed by Hoffman.
Amanda was the person who sent Cecil into the clinic, where he accidentally caused Jill to have a miscarriage.
The box Jill received in the previous film contained instructions on how to carry out Jigsaw's final wishes, including Hoffman's test.

When Lawrence cauterized his wound with a hot pipe at the beginning of the film, Jigsaw witnessed this, took Lawrence in, nursed him back to health and placed a prosthetic leg on him. Lawrence became Jigsaw's one true accomplice—while not an official apprentice, the only person trusted with the details of all the "games"—and willingly helped him with his schemes^Namely. The letter Jill delivered to the medical office in Saw VI was addressed to Lawrence; it contained a tape of Jigsaw telling him to act against Hoffman should anything happen to Jill as his final task, after which Lawrence would be given access to the remaining material that Jigsaw had kept for himself.

The film is partially a Stealth Prequel. The barn is one of the original Jigsaw's first "games" that took place at least a decade before the events of this film. Logan was one of the players in the Barn; he was spared and recruited by Jigsaw—then eventually became the new Jigsaw long after John and Hoffman's deaths.

Schenk faked his death, is the copycat killer, and has been targeting dirty cops because he witnessed Pete murder his father to prevent him from testifying to a crime.