Deliberate mistake: One of the bodyguard's rifle which is a Sig model SG553 only has a front sight and no rear sight. The rear sight can easily be attached to the Picatinny rail. Such a rifle is only good for up close instinctive shooting, anything at distance is spray and pray. (01:39:00)
Deliberate mistake: When Batman enters the replica of The Joker's apartment there's no place for The Joker to hide. Yet seconds after Batman enters, The Joker comes out of nowhere to hit him with a pot.
Deliberate mistake: During his autopsy in Saw IV, it is revealed John Kramer was 52 at the time of his death. Kramer's role in this film is the very early stages of his time as Jigsaw, shortly after his cancer diagnosis, which would put him in his early 50's. However, he looks far too old to convincingly be that young (Tobin Bell was in his mid-70's at the time of filming). He even looks older than he did when he was on his deathbed in Saw III.
Deliberate mistake: When Michelle brings up the photo of "Fake Denzel" on her phone, she says she put it into a hidden folder. Problem? She only presses on her phone once (based on the sound you hear), and has the photo up and filling the screen within about one second. Totally preposterous. Obviously, it was done that way to keep the scene moving quickly... but there's no way a single button press and a timespan of about one second is going to bring up and maximize a photo from a hidden folder on her phone.
Suggested correction: The very faint click you hear could be her phone unlocking, so we don't know how often she taps the screen. That said, yes, it's unlikely she'd be able to access the photo that fast.
I don't understand this correction, because it literally just seems to reinforce the original mistake. Unlocking her phone wouldn't instantly bring up a photo in a hidden folder.
Deliberate mistake: To meet Manny, Mike walks through his store. The last obstacle is a PVC curtain. The camera has to go through the curtain, moving it and thus revealing its presence. However, it is definitely a deliberate artistic choice. (00:32:50)
Deliberate mistake: At the end of the car chase with Penguin Batman's car drives upon a ramp at high speed before the explosions occur but his car only appears flying through the air and landing 15 seconds after the explosions. That's quite a long jump. (01:23:33)
Deliberate mistake: The F&F series always shows some amazingly advanced (and unlikely) technology; in this movie there is a big usage of electromagnets that are nothing short of miraculous. Not only they have a strength that would require them to have generators tens of times bigger than the cars they are on, and repel with the same ease as they attract; they also attract objects with varying° of precision and direction, all by turning their simple dial.
Deliberate mistake: A shot of the pile of ashes from the fire wherein Cassie's body was essentially cremated showed Nina's half of the broken heart necklace sticking out ABOVE the ashes, which would be impossible. Also, a metal charm on a chain that was around Cassie's neck would not survive the huge fire or be totally clean and unscathed.
Deliberate mistake: The Virtuoso (up several stories in a building) would not be able to hear what the boy and his mother across the street were saying. The boy even started to say "Hey, mom" when he was still exiting the building. (00:11:41)
Deliberate mistake: The (fake) confession letter was postmarked from Ohio and sent to Allison Connor, 331 Henry Lane in Hilliard, MB 21243. No U.S. state has a postal abbreviation of "MB." The way the "B" was written in thick bold letters made it resemble a "D" - "MD" represents Maryland (where the film apparently takes place). Also, there is no current 21243 zip code in the U.S. There is a 21241 for Baltimore City and the next consecutive zip code is 21244 in Baltimore County. The created address LOOKS real. (00:50:44)
Deliberate mistake: Carson's [John Travolta] cat Raymond did not appear to be in the pet carrier when he was running out of the building to his car or when walking to his office and placing the carrier on the desk. (00:02:15 - 00:03:30)
Deliberate mistake: It is unlikely that Kimmel shoving/ramming the beer bottles on the table using his dish and piece of steak in his right hand would shatter the beer bottles into such small pieces (or at all) like he did. (00:36:55)
Deliberate mistake: The front passenger's side mirror [driver's side is on the right] is parallel to the screen/camera yet there is a perfectly clear image of the passenger's face looking into the mirror. (00:00:38)
Deliberate mistake: One of the first shots in Greece shows Benoit Blanc and Lionel standing on the pier. As director Rian Johnson himself says in an interview for the Vanity Fair Youtube channel, "Matches nothing else in the scene lighting-wise, but it's gorgeous soooo...who cares." (00:13:30)
Deliberate mistake: Considering the position of the surveillance camera (height and angle - almost parallel to the side of the building as well as to the sidewalk), plus the lens being indented within the outer frame, it would not have been able to capture a view of Redd on the sidewalk below like it did. (00:24:40)
Deliberate mistake: The view looking out the windshield showed the man on the bicycle had stopped when he was in front of the car's passenger side, but the outside view showed the man still coming to a stop and then tilting his bicycle. (00:07:12)
Deliberate mistake: The thug wearing headphones and facing the money on the shelves did not notice that Savage forcefully opened the door several feet to his right, slamming it against the adjacent wall, or that Savage had entered the room. The bang to and vibration from the door hitting the wall should have been enough to overpower the sound from his earphones, but - even if they weren't - his peripheral vision should have sensed the door opening and Savage entering. (00:02:55)
Deliberate mistake: A car plummeting 10 metres off from a plane, landing on two cars as if they were a pair of soft gymnastics pit mats, just to keep on driving without a single scratch - let alone a mechanical breakdown or the blowing up of a tyre - defies all laws of physics and common sense.
Deliberate mistake: Ryan was cooking venison (deer meat) in a pan over hot coals. He speared a piece with his knife and held it up for his young son, Billy, to take, which Billy did with his fingers. But did not get burned or show any signs that the meat was hot. Billy was even able to take a bite of the meat. The meat could not have cooled off that fast, even outdoors in jacket-wearing weather. (00:07:04)
Deliberate mistake: The driver's side mirror would not be able to capture the view of the store that Monique is robbing - the mirror is slightly angled towards the rear of the car, plus Arthur's car is parked too close across the street. (00:00:33)