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: The picture on the wall of a younger Mike on a horse shows his groin against the horse's neck right below its ears - obviously photo-edited/photoshopped. (00:04:29)
Revealing mistake: Lower-third shots of the aquarium in the background at the Delaware Raceway's sports lounge were often blurred and did not look like they matched full views of the aquarium. (00:36:05 - 00:36:34)
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 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: In a sudden downpour, "rain" falls vertically, across a single line. (00:18:28 - 00:19:44)
Revealing mistake: When Maurizio has a water fight with one of the truck drivers, above the logo of the fictitious company "Corriere F. Reggiani" on the window of the truck you can see the logo of "F.lli Zucchetto", (Zucchetto Brothers) the real company owning the truck, who organizes real life gatherings of vintage truck owners. (00:22:50)