During the jail cell scene, Joaquin Phoenix breaks a real toilet. His actions were entirely improvised. Due to the historical past of the building where the scene took place, the toilet was considered "historical." Joaquin had no intentions to break the toilet, nor did he think it was possible.
After a few days of shooting, Paul Thomas Anderson noticed that Joaquin Phoenix would use the whole space where they were filming, even if it was outside the marks, so he told the lightning crew to have the whole space ready to follow Phoenix with the camera if necessary.
Drinking Jug-Juice, the NAVY slang for imbibing fuel mixed with cans of fruit, was detailed by the staff of the Aircraft Carrier, USS Hornet Museum - one of the locations utilized for the shoot. The scene in which Freddie gets ethanol out of the torpedo on the ship is also based on a true story told by Jason Robards to Paul Thomas Anderson.
Paul Thomas Anderson has acknowledged that L. Ron Hubbard and the Church of Scientology served as partial basis for the character of Lancaster Dodd and his cult, "The Cause." This revelation sparked much discussion in the press, as the Church of Scientology has a long history of litigation against critics of Hubbard. Though the Church released no official comment on the film, Anderson claims that when he screened the film for his friend Tom Cruise, an outspoken Scientology advocate, Cruise erupted with anger, specifically objecting to scenes where Dodd's son Val admits that Dodd made up the tenets of "The Cause," which parallels real-life admissions by Hubbard's son. Anderson has admitted to a heated exchange with Cruise, though both the actor and director have kept details of their argument, and the outcome private.
The trailers for the film were edited by Paul Thomas Anderson himself without any permission from the studio. The trailers were notable for consisting mostly of footage not featured in the final cut of the film.
The primary influence for the film was John Huston's 1946 Documentary: Let There Be Light (1946). Director Paul Thomas Anderson has stated that he was taking material from the film "left, right, and center". Producer JoAnne Sellar has also stated that they used the film as a reference for production design and costume design.
Paul Thomas Anderson initially wanted to put his own children in the film during the early scenes set at the portrait studio, but he decided against it because his mixed-race children did not have a period appropriate look.
The ship carrying the cult is named "Alethia", the Greek word for "Truth". It comes from the prefix "a-" and the word "lethe", which means oblivion. So it literally translates as "un-forgetfulness", which fits the intentions of The Cause of remembering past lives and forgotten memories.
In order to achieve the effect of clenching his mouth and talking out of one side, Joaquin Phoenix had his dentist attach metal plates to his teeth with rubber bands to hold them shut. The rubber bands weren't strong enough to hold his mouth shut, so he removed them. But the metal plates, complete with screws that slightly cut up the inside of his cheek, were enough of a constant reminder that it allowed him to play that aspect of the character.
Paul Thomas Anderson wanted a workprint to match the Avid cut, so he had his editors assemble the physical film daily to match the digital edit by hand. Anderson also bypassed the use of a Digital Intermediate instead color grading the film with a photochemical timer, which resulted in a higher film resolution due to less manipulation of the filmed image.
The first motion picture in 16 years to be filmed on 65mm format using Panavision's System 65 camera. Around 85% of the film was shot in this format, with the rest shot on 35mm. The last full-length motion picture to be shot in 65/70mm was Kenneth Branagh's 1996 adaptation of William Shakespeare's Hamlet (1996).
The decision to shoot in 65mm came from a desire to replicate the look of photos taken by vintage Pressman cameras, which use large-format 4x5-inch film. This also led to the use of the narrower 1.85:1 aspect ratio (65mm has a native aspect ratio of 2.2:1). Anderson initially suggested shooting the film in VistaVision, and test footage was shot in that format, but the shallow-focus effect was not pronounced enough.
Jeremy Renner was originally going to play Freddy when the film was prepped to shoot years ago, but when financing fell through, and Joaquin Phoenix was available following his I'm Still Here (2010) project, the filmmakers were able to cast him.
Paul Thomas Anderson premiered the film in a surprise 70mm screening at the American Cinematheque in Los Angeles in August 2012 following a 4k restoration of The Shining (1980), almost a full month before the official world premiere at the Venice Film Festival. Those in attendance were told before the start of The Shining (1980) that there would be a special free screening after the film, but did not reveal that the screening would be the world premiere of this film.
The New York Times reported in 2012 that Paul Thomas Anderson had originally conceived the idea of the film 12 years earlier, which would have been in 2000. Intriguingly, this was only one year after Anderson had directed the most famous Scientologist in the world, Tom Cruise, to an Oscar nomination in Magnolia (1999). At the press conference for the world premiere of the film at the Venice Film Festival, Anderson reported that he had screened the film for Cruise out of respect, but that Cruise and Anderson remained friends and any discussions between them would remain private.
The outtakes reveal that while filming the scene of Master and Quell smoking cigarettes after their first "processing scene," Philip Seymour Hoffman and Joaquin Phoenix kept cracking up after Hoffman's line, "I like Kools... minty flavor," including in the take that made it into the film. In the film, it cuts away just before Hoffman started laughing.