The Cast Showoff: Dudley Moore, a highly accomplished jazz and classical pianist, plays the piano at his engagement party. For bonus points, he performed the piano part of "Arthur's Theme" to accompany Christopher Cross on two television specials, starting with An Evening with Dudley Moore, which tied into the film's U.K. release.
I Am Not Spock: Dudley Moore became so associated with this role that he was rumored to actually be a serious alcoholic, especially as his health declined in the 1990s — which was really due to the progressive supranuclear palsy that ultimately killed him. (This wasn’t true for him, but it sadly was for his long-time comedy partner Peter Cook.) That said, Moore didn't mind the association otherwise, telling his friend/biographer Barbara Paskin in 1999 that "I really would have liked to have been like him. Less drunk."
In Memoriam: The sequel was dedicated to the late Steve Gordon, director and writer of the first film.
Money, Dear Boy: John Gielgud said that he didn't find the film or his lines particularly funny, much less interesting, and originally declined the role. It was only when the producers came back to him with an offer of a much larger paycheck that he eventually accepted.
One-Book Author: This was Steve Gordon's only directorial effort; he died of a heart attack at 44 in 1982. It was only his second produced screenplay, the other being The One and Only in 1978. (Prior to this, he wrote extensively for television sitcoms.)
Orphaned Reference: In the opening sequence, Arthur mentions that (among other things) he plays tennis when Gloria asks him what he does for a living. The scripted scene in which he and his father discuss the former's romantic woes over a game was shot — a still from it appears on the Australian poster — but cut.
The Other Marty: Bud Cort was originally suggested for the role of Arthur. Apparently, Cort was actually cast in the part, but withdrew prior to principal photography.
The Critic's creators were fond enough of this film and Maurice LaMarche's impression of Dudley Moore that their parody Arthur 3: Revenge of the Liver in Season One's "Eyes on the Prize" was spun into an entire Running Gag in Season Two where Moore/Arthur would pop up in the strangest places to crack jokes.
On Cinema built a Running Gag around Arthur being a favorite film of the in-universe Gregg Turkington, which figured prominently in the 7th Oscar Special episode (where he interviewed a Dudley Moore impersonator).
Sleeper Hit: One of those films that didn't open big — it was July 1981, when Superman II and Raiders of the Lost Ark were dominating the box office — but stuck around in cinemas long enough for it to find both major commercial success and even awards buzz. It was the fourth highest-grossing film of the year in the United States, only outdrawn by those two films and On Golden Pond, also making it the year's biggest pure comedy (edging out Stripes). Its sole weekend at number one was two months into its run!
Geraldine Fitzgerald was only 22 years older than Dudley Moore, despite playing his grandmother. However, as Moore was already over 45 when he played Arthur, finding a working actress who could plausibly be his grandmother would have been very difficult. She was also only eight years older than Thomas Barbour, who played her son, and Barbour had only fourteen years on Dudley Moore despite playing his father.
After the film's success, Dudley Moore was approached to reprise the role of Arthur in a Broadway musical Screen-to-Stage Adaptation but turned it down, not feeling that a perpetually-drunken character was suited to singing. (Said musical was eventually staged regionally in 1991-92, but got caught between the Moon and New York City, and never made it to Broadway.)
Gordon's original screenplay was subsequently published, and while much of it is virtually identical to the finished film (albeit with some scenes reordered and/or trimmed), there are several stretches that are significantly different:
Arthur and Linda leave the engagement party to have a drink at the Plaza Hotel, which ends up with them getting drunk and attempting a sexual tryst, with Arthur seriously considering just having Linda become his mistress (to her disappointment). In this version, it's Bitterman who finds them and breaks the news that Hobson is in the hospital.
Arthur goes to Linda's apartment rather than the diner where she works come his wedding day, and owing to what happened during their last night with each other in this version the reunion is hostile and violent (she socks him in the stomach...twice). He also learns that Hobson was the one who invited her to the engagement party.
The denouement has two major differences: 1) it's Arthur and Linda who convince Martha that she should let them marry so there won't be any working-class Bachs, and 2) Martha and Ralph meet each other, much to the former's chagrin, by way of setting up a final gag in which he passes out upon learning his daughter's marrying into millions.
Arthur 2: On the Rocks
The Cast Showoff: Once again Dudley Moore gets a scene showing off his piano-playing skills, this one set in a dive bar. He would often entertain the crew by playing the piano between breaks in filming.
Screenwriter Andy Breckman was allegedly disappointed by the sequel too, and went to his hometown theater just to hang around and apologize to the people who went to see it.
The Other Darrin: Jill Eikenberry, who played Susan in the first film, was replaced by Cynthia Sikes here.
Produced By Castmember: Dudley Moore received an "Executive Producer" credit. This is the only theatrical movie where Moore was credited in a producing capacity.
Sequel Gap: The movie was released seven years after the first, yet in the storyline, it is stated that it is five years since Hobson died, and six years since Arthur dumped Susan Johnson at the altar.
was created in which Arthur addresses the audience from his bathtub. The final trailer averted this trope, by contrast.