* ActingForTwo: Creator/PeterSellers also played Jessica Marbles' taxi driver, but the scene was deleted.
* AllStarCast: Including Creator/PeterFalk, Creator/EileenBrennan, Creator/AlecGuinness, Creator/DavidNiven, Creator/PeterSellers, Dame Creator/MaggieSmith, Creator/EstelleWinwood, a young Creator/JamesCromwell, and a rare acting appearance by Creator/TrumanCapote.
* CreatorBacklash: Creator/PeterSellers hated the script and thought the movie would be an absolute bomb. It was a smash hit.
* DeletedRole: Creator/PhilSilvers had a small role in this film, but his scenes were deleted in the final release print.
* DeletedScene: Several additional scenes were included in the film's network-TV airing. None are available on the DVD release, but all can be found (albeit in poor a/v quality) on Website/YouTube.
** Dick and Dora Charleston encounter Tess Skeffington traveling on foot en route to Lionel Twain's. See [[https://www.youtube.com/watch?v=Ge77QeBmlpE here]].
** Miss Marbles converses with a taxi driver (also played by Creator/PeterSellers, using his [[Radio/TheGoonShow Willium "mate"]] voice) on arriving at Twain's. See [[https://www.youtube.com/watch?v=QHEiT8VXUyQ here]].
** Willie Wang gloats about having discovered his own "clue", which turns out to be worthless. See [[https://www.youtube.com/watch?v=qxsBS97T4q8 here]].
** Finally, expies of Literature/SherlockHolmes and Dr. Watson arrive late, after the whole thing is over. See [[https://www.youtube.com/watch?v=R5oBeFUDllM here]].
* FakeNationality:
** British actor Creator/PeterSellers as a Chinese detective. Likely a parody of how Film/CharlieChan had never been played by a Chinese actor ([[WesternAnimation/TheAmazingChanAndTheChanClan in live action]]). It is later revealed he was actually either [[spoiler:Lionel Twain's illegitimate son or adopted and raised by Twain]]. In either case, no explanation is given for his speech.
** American actor James Coco plays Milo Perrier, who (depending on which line of dialogue you believe) is either a Frenchman or a Belgian.
--->"Never underestimate a Frenchman's nostrils, Miss Twain."
--->"I'm not a Frenchy! I'm a Belgy!"
** Not to mention fellow American James Cromwell as Perrier's chauffeur Marcel.
* FollowTheLeader: A 1980 MadeForTVMovie titled ''Murder Can Hurt You!'' took this film's concept and aimed it at '70s police shows with characters such as [[Series/{{Kojak}} Nojack]], [[Series/McCloud MacSkye]], [[Series/{{Columbo}} Lt. Polumbo]], [[Series/PoliceWoman Sgt. Salty Sanderson]], and [[Series/StarskyAndHutch Studsky & Hatch]].
* PlayingAgainstType: Sir Creator/AlecGuinness as a strange butler may surprise people, as well as Peter Falk playing a Humphrey Bogart-style hard-boiled detective instead of his usual Series/{{Columbo}}.[[note]]The trench coat that Peter Falk wears in several scenes is the same one he wore on Columbo. It belonged to him, and he wore it in a couple of other films, such as his cameo in The Great Muppet Caper.[[/note]]
* StuntCasting: Creator/TrumanCapote as Twain.
* ThoseTwoActors: Creator/PeterSellers and Creator/DavidNiven had previously costarred in ''Film/ThePinkPanther1963'' and ''Film/CasinoRoyale1967''.
* WhatCouldHaveBeen:
** Creator/OrsonWelles was originally considered to play Sidney Wang but had a scheduling conflict.
** Creator/MyrnaLoy was originally offered the part of Dora Charleston but she declined, later stating that "it would have been ridiculous to have Myrna Loy doing Myrna Loy". She also stated that she didn't want her "ass pinched by Creator/DavidNiven".
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