Mister Roberts began as a 1946 novel about the struggles of a junior officer aboard a US Navy supply ship that's suffering under the command of a tyrannical captain. The novel was then converted into a 1948 Broadway theatrical production, starring Henry Fonda in the titular role, which became a Tony Award winner and a long-running production. By 1955 Hollywood took notice and converted the play into a film starring Fonda as Roberts, Jack Lemmon as the eager Ensign Pulver, James Cagney as Captain Morton, and William Powell as Doc, Roberts' ally in the long-standing war against Morton.
Bittersweet Ending: Roberts gets the transfer to combat duty he wanted, but dies as soon as he gets there. The bosun requests the letter describing Roberts' death, to post for the crew of the Reluctant; instead, Doc has him post Roberts' own letter, thanking the crew for his transfer and praising them. Ensign Pulver, who has been afraid of confronting Captain Morton the whole movie, realizes he's letting Roberts down... and charges to the replacement palm tree, tosses it overboard despite the guard, and storms into the Captain's office:
Pulver: Captain! It is I, Ensign Pulver, and I just threw your stinking palm tree overboard! Now — what's all this crud about no movie tonight?
The Captain: Morton, only in title. He's really The Neidermeyer. Roberts is the one really running the ship. And Morton knows it. Which is one of the reasons — the other is sheer spite — why Morton refuses to let Roberts go.
Corpsing: Cagney reportedly had to ask Lemmon to run through one of their scenes several times before filming to get this out of his system, and still just barely managed to keep a straight face.
Dawson Casting: Fonda was 49 when the film was made, which seems pretty old for a junior grade lieutenant. It's argued that the film production was mostly Fonda's effort, who had played the role for years on stage.
Executive Meddling: Hollywood execs believed that Henry Fonda had been gone from film so long (he spent 8 years in self-imposed exile on Broadway) that they feared he wasn't a bankable name. However, Fonda's years on Broadway included playing the title role, and he was a major backer in getting the film made.
Production was plagued by re-shoots and directorial changes. John Ford was the original director, but he sucker-punched Fonda on the jaw one day, and Fonda retaliated by getting Ford thrown off the movie (a later medical emergency kept Ford off production for good). Mervyn LeRoy was brought in to complete production, who tried to film the same way as Ford's style to ensure a seamless product.
Additional re-shoots had to be done by the Broadway director Joshua Logan when Fonda and the producers felt some scenes just weren't working right.
Face Palm: Morton, in the last moments, when he realizes that Pulver is going to be as much of a thorn in his side as Roberts.
Fate Worse than Death: Roberts wants nothing more than to leave the USS Reluctant and the odious command of his Captain. Captain Morton knows this, and knows full well that — even worse than a court martial — the worst thing he can do is keep Roberts right where he is.
Subverted when Roberts gets his wish at last... and he dies with days of leaving the Reluctant.
A Father to His Men: Roberts. He's the one who really runs the supply ship, and he takes care of the men. Completely averted with the ship's official captain Morton.
His Quirk Lives On: At the end of the movie, Pulver seems determined to take up annoying the Captain the same way that Roberts had.
I Gave My Word: How Morton gets Roberts to stay silent on their deal over liberty for the crew. Part of Morton's backstory was how he resented college-educated officers like Roberts, but he also knew full well that someone like Roberts can never go back on his word.
What Morton doesn't realize is that college-educated guys like Roberts can figure out a loophole like angering Morton into making an open confession so that Roberts can legally claim he kept his word. After all, Morton never said anything about that palm tree...
Doug Roberts: Frank, I like you. There's no getting around the fact that you're a real likable guy. Ensign Pulver: Yeah? Yeah! Roberts: But... Pulver: But what? Roberts: Well, I also think you're the most hapless, lazy, disorganized, and in general most lecherous person I've ever known in my life. Pulver: I am not! Roberts: You're not what? Pulver: I am not disorganized!
Is This Thing Still On?: Morton leaves the mike to the ship's PA switched on when screaming at Roberts. This lets the crew know the truth about Roberts strange behaviour and that Morton is really the one to blame.
Jumped at the Call: Roberts is eager to serve on the front lines of the war but is stuck on a supply ship that's miles away from any action.
Kneel Before Zod: When the crew realise the Captain's precious palm tree has vanished from its pot (Mr Roberts having thrown it overboard) they all kneel before the empty pot and pretend to worship it.
The Medic: The ship's doctor, nicknamed appropriately enough 'Doc'. He's also Roberts's best friend on the ship and the one who realizes Roberts made a secret deal with the Captain, explaining Roberts's surly anger during the second half of the story.
Persona Non Grata: It's understandable why the crew of the "Bucket" would not be allowed ashore on Elysium again, after hearing what they did while on liberty there.
Reality Is Unrealistic: Yes the US Navy really did make a fuss about shirts. The reason wasn't just pettiness though. It was found out by the medical branch that shirts provided protection against burns in the case of an explosion.
Suspiciously Specific Sermon: On VE Day, Mr Roberts is listening to the radio and hears someone giving a speech on the need to destroy the symbols of tyranny and oppression. "You must tear up its roots like a poisoned tree, and cast it from the earth!" Inspired, Roberts salutes the radio, then throws the palm tree of his tyrannical captain overboard.
Took a Level in Badass: When Pulver realizes it's up to him to stand up to the tyrannical Captain. In the film, he breaks the chain from the bulkhead and chunks the new palm tree, bucket and all, over the side.
Well Intentioned Replacement: After giving away Ensign Pulver's half bottle of whiskey as a bribe to secure a visit to a liberty port, the officers discover that Pulver had promised it to a nurse. They create a substitute out of medical alcohol, Coca-Cola and hair tonic. It is surprisingly effective.
Wham Line: Just before the ending. "Mr. Roberts is dead."