Revealing mistake: At Wendy's 50th birthday party, the helium balloons did not move, even when her daughter Liz walked next to some of them while carrying a birthday cake with lit candles. (00:01:44)
Revealing mistake: If you look at the drawing in front of Eddie when he glances down at it after Venom typed in the name of the beach, it's only a crude draft of the one in close-up (it's missing the wave lines below the cliff outline, for instance). (00:11:20)
Revealing mistake: Maurizio tosses on the table the newspaper with the article about the new "P.G." brand launched by his cousin Paolo. The article itself is a copy/paste of the same paragraphs repeating a bit of history of the Gucci family and brand. (01:11:05)
Revealing mistake: The blue framed window the girls walk in front of after exiting the VW bus parked along the curb is presented as part of an extension of the house, but not when there's a front view of the entire house. The windows are actually aligned with the front door. (00:11:44 - 00:15:00)
Revealing mistake: While Martin is being mauled on the ground by Valentine the zombie tiger, he is being thrown up and down and side to side. There are a few seconds where the tiger takes a small break and watches him try to crawl away, but his body is still swaying around as if he still being grabbed by the tiger, but the tiger is not touching him; they did not match the animations of the tiger with the physical acting of the actor properly.
Revealing mistake: When Teddy's Cadillac Seville is blown up, you can see that the engine, transmission and catalytic converter have all been removed.
Revealing mistake: When Knox pulls up behind the parked BMW, the BMW's red tail light reflectors are not real (and maybe the car isn't, either). The reflector on the right side, in particular, is not fully connected to the car. (00:03:55)
Revealing mistake: There was already a gap in the snow mounds (which looked like a snow sledding path with no fresh tracks) when the "kid" was sledding down the steep hill. (00:02:40)
Revealing mistake: During the attack on Druig's village, there's a shot of Gilgamesh and Thena running towards the camera, then stopping as two Deviants fly over them. During this scene, you can see Don Lee (Gilgamesh) briefly look straight at the camera (he's not looking at either the village or the Deviants, since they headed in the opposite direction). (01:13:50)
Revealing mistake: When "Snowball" is sleeping on Lena's bed, it is obviously a "stuffed double" (stand-in). Snowball is usually partially hidden behind the dog (so breathing doesn't need to be shown/mimicked). The failure of Snowball to make even a slight movement is a giveaway (e.g, no ear movement when Lena starts talking), but even the stuffed lion, in itself, is not a very good replica - it simply looks fake. (00:33:44 - 00:48:20)
Revealing mistake: When Alana is walking toward the students, the hedges are mostly dark green, sheared level across the top, and reach to her elbows. Later (after Gary tells Alana he will take a mirror), the hedges turn mostly yellow and flower-like across the top, are quite uneven, and are as high as her shoulders in spots. (Use of a green screen is apparent). (00:00:40 - 00:01:26)
Suggested correction: One look at the scene make it apparent this entry is totally incorrect. The bushes look natural. The yellowness is just colour grading. There is no sign of green screen usage whatsoever. It would make no sense for this film, especially if you realise that director PT Anderson is known to be very much against the use of any sort of VFX or green screening.
Revealing mistake: The hubcap on the road that the "Black Saints" boy tramped on was a prop. He stomped on one side of the hubcap in his sock (his shoe had fallen off while running) and the other half that was not under his foot rose into the air. Also, when Harold picked up the hubcap, it was flexible (rubbery) and curved. (00:05:38)
Revealing mistake: After he takes his plate carrier off which looks suspiciously light, the rest of his armor is air-soft gear meant to stop BB's, not high power 5.56 rounds. (01:43:00 - 01:45:00)
Revealing mistake: Scottie (with Jamie) drove away in a blue four-wheeler that had a cab area (front windshield, roof, and four support bars or frame). At times, the four-wheeler did not appear to have a roof, the windshield was not visible, and the frame was gone - indicating they were not in an actual four-wheeler during these filming times. (01:13:58 - 01:16:00)
Revealing mistake: The door to Sharyn's room enabled her to look down the long hallway, but after she saw the man with the bloody face near her door, there was a hallway to her left instead of in front of her. (00:08:55)
Revealing mistake: After the coach [Michael Jai White] told Billy that the group of people present all chipped in to pay his entry fee, there was loud cheering ("Yeah!) but it wasn't obvious from where the cheering was coming - except when there was a close-up of a particular person. Otherwise, the people in the crowd - especially those closest to him - did not appear to be cheering. The cheering, as well as the people in the background (green screen), must have been added. (00:04:08)