Continuity mistake: Joe has 'Rick C' (his partner) listed as a contact in his phone - late on in the movie when Joe calls him from the bathroom stall, he is listed as just "Rick"
Continuity mistake: Finley carried her violin and one square suitcase out of her room to go to her audition. Sean parked at Dublin Airport and removed Finley's luggage from his trunk - two rectangular suitcases, neither matching the one Finley had. (01:44:25 - 01:45:21)
Other mistake: William Tillich (AKA Bill Tell) had one suitcase which could not possibly hold enough sheets (or thin blankets) to cover/wrap all the furniture in his motel room like he did. (His suitcase was not very large and also contained his clothes.) He covered an even larger area of furniture in Gordo's house. It isn't clear if he used his own sheets or just happened to find the same kind in Gordo's house.
Revealing mistake: At first glance, the cow at the start may have looked real, but its limited mouth movement while eating grass (without any grass being pulled out) indicates it was a mechanical cow. The cow also did not move its rear end or raise its head when Fenn and Geary approached and stood right behind it. A real cow would not stay in the exact same position (motionless) that amount of time. The cow's "fur" also did not look real. (00:02:50 - 00:03:24)
Revealing mistake: DEA Agent Rick Bowden was already seated "in the best position" before knowing where Ross would sit in the SF library. Chris Tarbell already had a surveillance camera behind the seat Ross chose, giving him a clear view of Ross, also before knowing where Ross was going to sit. Even if there were cameras in other positions, the DEA Agent and Chris Tarbell being at the right spots in advance was too coincidental to be by chance alone. (00:02:09 - 00:02:30)
Factual error: Unless left in the vehicle (not the case here), towed impounded vehicles do not have keys. Moreover, lacking keys, a valid registration, possibly proof of insurance, and new plates, vehicles bought at a NYPD auction are to be TOWED away. A newly-purchased auctioned vehicle, such as the Navigator in the movie, is "ticket-" or "citation-ready", not ready to be driven on the streets.
Other mistake: Packie arrived at Frank's garage on a bicycle, wearing a brown coat, hat, gray hooded sweatshirt, patterned shirt, and a T-shirt. Swaino arrived on a motorcycle, wearing a tight jacket, no hat, black gloves, and black jogging jacket with white trim. When they were outside by the grill, they had large sweaters over their coats. It isn't known where these sweaters came from. It can be assumed the blanket Swaino used at first was from Frank's garage, but the sweaters did not appear to be Frank's. (00:25:32 - 00:37:35)
Factual error: Before Tom landed in the puddle, there was water dripping or it was raining on it, but it wasn't raining when he was on the rooftops. After Tom landed, the water drops/rain suddenly stopped. Even if the water drops were from earlier rain running off the roof or other parts of the building, they would not be hitting the whole way across the puddle or that far away from the edge of the building. (00:02:34)
Continuity mistake: When Hagmaier is in the Florida State Prison room waiting for Bundy, his hair changes. Initially, his short bangs are straight across the middle of his forehead. When Bundy sits down, Hagmaier's bangs and top of head are "fluffier" (perhaps blown dry) and combed to the side. (00:11:05)
Factual error: "The Waltons Homecoming" is a remake of the 1971 TV-movie that led to the 1972-81 television series "The Waltons." In one scene, John-Boy has written a story for The Boston Arts Scholarship Competition. He addressed the envelope to "1815 Redwood St, Boston MA 02122." The movie is set in 1933. The Postal Service did not introduce ZIP codes and two-letter state abbreviations until 1963.
Continuity mistake: Before Jen gets on the yacht, Aileen's green halter strap can be seen because the left side of her hair is on or over her shoulder. When Jen gets on board, Aileen's hair is in front, covering up the green strap. The camera shifts when Lewis is hugging Jen and Aileen's green strap is visible again with the left side of her hair behind her. There is no noticeable wind and Eileen is standing in the same place. (00:32:10)
Continuity mistake: Ed Harris plays a property manager character and is featured in the beginning of the movie, walking with a pronounced limp, a seemingly painful gait. His character is shown in many other nominal scenes throughout the movie without limping. Most notable, shortly before the end of the movie, his character is shown dancing wildly, spastically, and jumping to music, seemingly unencumbered and fluidly, in a way that his character in the first part of the movie would not have been capable of doing.
Factual error: At the end of the film, Hellfire Jack returns the toy soldier to the son of the late William Hawkins in 1917. Hawkins son is shown taking it upstairs and placing it in front of a photo of his father, in between two medals. These are the British War and Victory Medals - these did not exist until 1919, and in most cases were not even issued until the 1920's.
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.
Factual error: All Arabic texts in the film suffer from wrong directional rendering. Arabic is a right-to-left language. Its letters have different joined and disjoined forms. The film, however, has rendered Arabic texts from left to right in disjoined letters. These texts aren't semantically wrong, though. For example, deciphering the Arabic message at 0:40:45 point gives "أليس "التنين فنان؟ Translation: "Isn't the Dragon an artist?" The film has even adopted a good font for them.