Most of Adam's lines to Lawrence throughout the first half of the film could be considered comedic gems.
"Nothing. I went to bed in my shithole apartment, and woke up in an actual shithole. What about you?" "My name is Very Fucking Confused! What's your name? What's going on here?" "I'm having a blast! This is the most fun I've had without lubricant!" [When Lawrence insists Adam has been hiding things from him] "Oh, well, let's see. On my sixth birthday, my best friend at the time, Scott Tibbs, stabbed me with a rusty nail, I didn't tell you about that. I didn't tell you that my last girlfriend was a feminist vegan punk who broke up with me because she thought I was too angry. I also haven't told you that one of my toenails is slight—" "I don't give a crap if you covered yourself in peanut butter and had a 15-hooker gangbang!" "Give me that sweet cancer!"
When Adam searches the toilet for anything that might help Lawrence and he escape, he first dunks his hand into the filthy bowl, eventually coming up empty handed. He then checks inside the clean tank and immediately finds the bag Jigsaw left for them. He dryly remarks, "Wish I'd checked in there first."
Adam's Bad "Bad Acting" when he tries to convince whoever's watching that he's actually dead.
While Lynn and Amanda are arguing in a room filled with unused traps.
Amanda: I'm sorry, I know it's hard to concentrate when you're surrounded by so many things you could kill me with.
Followed by Amanda offering Lynn an axe and talking her through why killing them and escaping is a truly terrible idea. You get the impression that Amanda is trying not to laugh the whole time.
Strahm's complete and utter exasperation with Jill when she refuses to give a straight answer during her interrogation:
Strahm: That's sweet, Miss Tuck, but if you love the guy so much why leave him? Jill: He left me long before I left him. Strahm: Okay, people break up, relationships end, it's called life. He started massacring people. Jill: Gideon meant everything to him. Strahm: Gideon? I'm sorry, who? Jill: Do you know anything about the Chinese zodiac? Strahm: Aw Jill, no, no-
When Zeke comes home and senses that someone might be in his apartment, he has his gun at the ready just in case… only for it to be his father Marcus, which leads to the following exchange. It’s the delivery between Samuel L. Jackson and Chris Rock that makes it.
Marcus: You pulled a gun on your old man? Are you out of your fucking mind? I could’ve killed you! Zeke: What are you talking about? I got the gun. Marcus: (holds up his own gun) I could’ve killed you.
At the end of the film, after the SWAT team unintentionally activates Marcus' trap and his restraints begin lifting him up again, out of a mixture of drowsiness and shock, he can't help but wonder aloud, "The fuck goin' on?" — and given it's Samuel L. Jackson saying it, it makes for a weirdly funny bit in an otherwise extremely dire scene.
Amanda then provides additional "translation" for John when he explains the outcome of Valentina's trap in fairly expospeak fashion.
Valentina: Are you fucking crazy? What makes you think I’d fucking cut off my own leg? John: Because if you don’t, the wire saw that’s wrapped around your neck will first cut into your skin, then your vertebral ligaments, and finally, it’ll sever your spinal cord. Valentina:(whimpering) No! Amanda: The CliffsNotes version? It’s gonna cut your head off.
Video games:
In the second game, Michael finds out that one of the things he has to do is blow open a gate with chemical explosives. It's all in the delivery: he just doesn't sound surprised anymore at how his night's turning out.
The commentary track, with Leigh Whannell, Cary Elwes, and James Wan. They have a total blast and mock the film a ton, as well as share several funny stories. And Cary even does a Marlon Brando impression. Apparently Leigh was the production team's Butt-Monkey as well:
James Wan: We peed in the bathtub. We all took turns peeing in there. We told Leigh it was Lipton Tea.
The Easter eggs. Of particular mention is "Saw in 60 seconds," where the whole movie is reenacted with BARBIE DOLLS, and the cast and crew talk about Billy the Puppet as if he's an actual actor.
While the credits roll during the commentary, Leigh says that he's invented a drinking game based on Saw: finish your shot every time, while watching the commentary, James mentions how he only had 18 days to film the whole movie.
