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 lighting crew to have the whole space ready to follow Phoenix with the camera if necessary.
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.
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.