All spoilers, including those from following movies, will be unmarked ahead. Read on or go back — make your choice.
Fridge Brilliance:
- When Cecilia asks John what he does for a living, he tells her that he "helps people work out their emotional problems and make positive changes in their life." A great bit of dark humor, but also a good reason for the usually-honest John to lie right to Cecilia's face— early in his Jigsaw career at this point, he wouldn't want the fact that he's a professional engineer to be known, lest the connection be made that only someone with his skills could create the mechanisms necessary for his games.
- Ever since it was first shown in promos, the Eye Vacuum Trap has garnered some criticism for seeming like an under-baked idea compared to most other traps in the franchise. In the film proper, it's revealed that the trap's scene is an Imagine Spot that John has when he sees a custodian stealing from a patient - but he refrains from going through with it when the guy thinks better of the theft. In other words, it's literally an underdeveloped idea that just popped in John's head.
- More evidence on how underbaked the idea is the notable absence of any lethality. John's traps for the most part involve his victims to maim themselves or die; the Eye Vacuum Trap has two maim options; you break you fingers before the time limit, but if you fail, you lose your eyes (along with any fingers you've already broken). This is important because John's philosophy centers on forcing someone into a life-or-death situation, so that after survival, they become more grateful of living and change their lifestyle. John appears to have gotten preoccupied with the "punishment" part of the trap.
- When John tells Cecilia over the phone that he was referred to her by Henry Kessler, Cecilia smiles and says "Henry, he's doing well, I'm so pleased." John would have thought that Cecilia was referring to Henry's health as her patient, when she probably actually meant that Henry is doing very well as a scout consistently sending her high-value targets
- Henry is quite muscular for someone "suffering" from Stage 4 pancreatic cancer — a cancer notorious for causing cancer cachexia, due to both its more delayed diagnosis compared to other cancers and the importance of insulin in maintaining muscle mass. Henry's incongruent fitness is even lampshaded by him arriving to the cafe on a racing bike.
- John bonds with Carlos by fixing the latter’s bike; the tricycle Billy uses is revealed in the fourth film to be John’s own tricycle (or replicas, considering the Billy puppets he burns through) and John sketching a tricycle in Jigsaw suggests a fondness for bikes, so seeing a fellow bike enthusiast struggle made John more drawn to help the kid.
- All the traps that John sets up for the Back-Alley Doctors mimic different medical practices:
- Pipe Bomb Trap: Cancer surgery, with Diego having to remove the pipe bombs or “cancer” from his body.
- Bone Marrow Trap: Amputation and bone marrow transplantation.
- Brain Surgery Trap: Brain Surgery, obviously.
- Radiation Therapy Trap: Radiotherapy, with the name of the trap being just an unabbreviated version of the term.
- Bloodboarding Trap: Blood transfusion.
- Burning Gas Chamber Trap: Anaesthesia.
- Given who the victims are and the nature of their traps (surgically removing pipe bombs, performing self-craniotomy, escaping the radiation of an x-ray machine), it's highly likely that Dr. Gordon was heavily involved in conceptualizing and designing them. This can't be a surprise, given his profession — he wouldn't tolerate medical malpractice.
- Cecilia's name is a female version of "Cecil"; Cecil Adams was the name of the drug addict who killed John and Jill's unborn son Gideon and was the first person tested by John. Both people are catalysts of John's arc; Cecil's actions kickstarted John's Start of Darkness, while Cecilia's betrayal by conning John prevents him from considering to end his crusade.
- Gabriela's death is most likely what inspired John to let Amanda oversee the events in the Nerve Gas House. As explained in the house's pre-game flashback from Saw V:Hoffman: You're assuming this is going to play out the way you want it to.
Kramer: I assume nothing. I anticipate the possibilities and... I let the game play out.
Hoffman: Then why do you need Amanda in the game?
Kramer: To ensure that the rules are followed. She won't make decisions for anyone. She will just... offer choices. - On the other hand, it's also possible that Amanda's experience with Cecilia and her fellow scammers contributed to her deciding to create inescapable traps in Saw III. This experience, doubled with what she went through with Xavier in Saw II, is probably what ultimately convinced Amanda that Humans Are the Real Monsters who are willing to screw others over for their own selfish goals and that John's methods aren't gonna change people like Cecilia and Xavier for the better, and so decided to pervert John's philosophy and never give her victims a chance to escape from their predicaments at all. It also explains why Amanda is so hostile to Lynn; her last experience with a "doctor" who tried to treat John's cancer didn't go so well for both of them.
- Cecilia, in retrieving Valentina's intestines as a rope, volunteers to do the equivalent of Amanda's test in the first movie, not for a guaranteed freedom from her trap, but for the mere opportunity to send out a phone call. Cecilia does so with less dignity for the corpse and no trauma at all, immediate or lingering.
- In terms of general concept and execution, the Brain Surgery Trap is similar to Saw II's Death Mask, only that it's WAY more brutal. Since Saw X takes place before Saw II, this suggests John regretted going so hard on Mateo, since he reused the concept for Michael's trap with a MUCH easier sacrifice to make and a far more humanely death in comparison.
- The easiest way to tell that the Bloodboarding Trap is a dupe? There's no tape accompanying it.
- John actually thought even further ahead for the Bloodboarding Trap than it seems. The tape accompanying the Gas Chamber trap that acts as Cecelia and Parker's actual test notably doesn't contain anything pertaining to the killing mechanism of the trap itself, only telling the two of them that they'd need to fight each other to determine the sole survivor. Both the Bloodboarding Trap and the Gas Chamber Trap are competition traps where only one participant survives, meaning the tape could be used for either of them.
- An arguably even easier way to tell: it's a two-person trap that was meant to be used on only one person. Parker even mentions that doesn't make sense.
- Parker's doubt is also roughly Five-Second Foreshadowing to the reveal that John knew Parker would show up — he would have been Cecilia's opponent, most likely if he had complied with the "no guns" rule and followed along with John, thus giving him a genuine chance to live.
- There's a big parallel between John and Cecilia. Both of them play on peoples' hope and desire to live, but manage to be inverted in just about every other aspect.
- John finds people who are relatively healthy and frightens them with the threat of death. Cecilia finds people who are dying and lures them with hope for life.
- John does what he does because, in his own twisted way, he thinks he's genuinely helping people; he is, however, widely considered a monster, both in and out of universe. Cecilia does what she does out of self-serving greed, but her patients see her as a saint — one woman even calls her an angel.
- John finds people himself and takes them by force. Cecilia waits for people to come to her.
- John sees his cohorts as family. Cecilia sees her cohorts as expendable labor that she has to split money with.
- Cecilia's fate at the end: sit and wait hopelessly for death to come. The exact fate she left her cancer-ridden scam victims with. On top of that, John punished her in the same way she scammed him. Cecilia baited him with hope, only for her to snatch it away. John tricked her and Parker into activating the final trap and while Cecelia emerged victorious, it was ultimately a Pyrrhic Victory because while she survived, she can't get out of the trap and has only extended her life possibly by only minutes.
- The deleted post-credits scene shows that the door unlocks when the timer hits zero, which serves as a blow not only to her character, but her perception of John's ideology. Had Cecelia and Parker truly been in it together as they claimed, they could have taken turns breathing in fresh air until the timer ran out. The door unlocking also shows that John does have some mercy in him, and is not necessarily a senseless murderer as she claimed. It's also an example of John using Cecelia's own methods against her: feeling trapped in a hopeless situation, she's lured in with a guaranteed promise of survival without exhausting every other option.
- The poison gas was likely able to enter Parker's bloodstream quicker through the cut on his cheek, explaining why his skin was shown visibly rotting while Cecelia's wasn't.
- Before starting the game John said something along the lines of "you either play the game or you don't", with the latter option leaving you more likely to die horribly in a medieval deathtrap. Despite being told this, Cecilia throughout the game tries to weasel her way out of it, steal back her phone to call for help (doing so successfully), and after escaping thanks to Parker, she forces John and Carlos (who inconveniently showed up) into the trap she and Parker were supposed to be a part of and leaves them to potentially die. In hindsight, considering her fate, she should've just played the game as she was supposed to.
- Compared to the other ones, the Bloodboarding Trap is the least tortuous and complicated trap with the highest chance of survival: all Parker and Cecilia would have to do is take turns activating the levers so that each of them gets drowned in blood while the other gets a chance to breathe and just keep doing that until the blood tanks run out. Ideally, she and Parker would have played, one or two of them would survive, and they would leave without their money, but alive and hopefully better people. But as John foresaw, Parker and Cecilia would break free, refuse to play, instead forcing John and Amanda in their place, and try to steal back the money in the office.
- Cecilia ends up forcing John and Carlos into the trap, while she and Parker go to the control room to get their money. After taking out what she assumed to be her money (really a decoy bag filled with copies of bank statements detailing her fraud), she activates a trap that fills the room with poisonous gas that'll kill her unless she's able fight Parker to the death over the only ventilation hole in the room. She wins thorough sheer ruthlessness by mortally wounding Parker with the piece of metal she'd been using as a knife, but she's still stuck in the room; the gas had started to affect her and even though her head is out of the room, her demise has only been momentarily postponed.
- Cecilia's true test was the Bloodboarding Trap: by refusing to play John's game, alongside senselessly killing Gabriela (who had survived her trap and earned her right to live in John and Amanda's eyes) and forcing Carlos, an innocent boy, to get tortured and potentially killed by the trap she was supposed to escape all out of pure evil, Cecilia throws away her chance at redemption and so fails her test, so she is punished with a partially inescapable trap that will leave her to die a slow painful death.
- The true test being the Bloodboarding Trap explains why the Gas Chamber Trap breaks John's fundamental rule: that you get to live if you survive your game. For all of his hypocrisies and debatable morality, John does not play on the details with that rule, if you win you are free, not let to die for another reason. He also tells several time his apprentices not to let their emotion or judgement cloud their actions, which means he wouldn't rig the trap just for personal reasons. However, that only applies to players of his games and, as stated in the first point, Parker and Cecilia weren't, and there are no similar rules to dictate how he will punish you for breaking the rules, and it's actually consistent with John's established MO of not being prone to give a second chance. You can also tell it's not a real Jigsaw trap by the condition required to win: them turning on each other is poetic, but doesn't really teach them anything, since they have no issue about using and sacrificing others. Jigsaw made a similar trap before (although, chronologically is after), but in that the winner was supposed to cut off their own flesh, making it a pretty steep personal cost, cost absent in this one. Hence John is not testing them, is just yanking their chain as he punishes their selfishness.
Fridge Horror:
- Diego wakes up with each scalpel securely taped into his hand because he might not be able to keep hold of the scalpel with whichever arm he mutilates first by cutting through flesh, muscle and nerves. In other words, the hand of the first arm will be rendered too disabled to hold the scalpel - and the same fate awaits his second hand and arm if he is to survive the Pipe Bomb Trap.
- Amanda attempting to spare Gabriela is likely why she died. She decided to run Mateo's game instead of hers, meaning that Gabriela's came third - and so ended mere moments before Parker grabbed the gun and freed Cecilia. If Gabriela had gone second, John and Amanda likely would have prioritized getting her medical attention (or at least out of the room) before continuing. This extra time would have allowed her to avoid getting killed by Cecilia.
- John's hypocrisy is further uncovered when you think a bit more about Gabriela's fate. He and Amanda lured Parker into the game, and then John took special care to remove the gunpowder from each of the bullets in Parker's gun (so that the weapon would have the same weight as a ready-to-fire one, but would actually be harmless). They allowed Parker and Cecilia to retrieve the gun and capture them so that they would be fooled into thinking they had turned the tables to their advantage. Cecilia then proceeds to break Gabriela's neck with her foot. Gabriela would have lived longer (but the burns didn't exactly help her long-term prospects, see the Headscratchers page for more on that) if John and Amanda had not allowed for this to happen. But it did happen, because the killers put the continuing push of the game and getting one up on Cecilia and Parker over their ostensible sense of fair play to protect and offer medical assistance to the trap participants after winning their tests (which many viewers believe helps to humanise the Jigsaw team in this film).
