The film stars Will Ferrell and John C. Reilly as the eponymous characters Sherlock Holmes and Dr. Watson, respectively; with Rebecca Hall, Rob Brydon, Kelly Macdonald, Steve Coogan and Ralph Fiennes in supporting roles.

First announced in 2008 with Sacha Baron Cohen as Holmes and Ferrell as Watson, Holmes & Watson languished in development hell for several years before Ferrell and Reilly were confirmed for their eventual roles in July 2016, and Etan Cohen was announced as director.

At the trial, Holmes reveals the man accused of Moriarty's crimes is an imposter named Jacob Musgrave, who is incapable of committing the murders due to tremors in his hand caused by excessive masturbation.

By the end of the autopsy, Watson declares that the corpse's cause of death is indeterminable, while Holmes believes that the person was poisoned.

Holmes goes to Watson's cell, only to find it empty save for a plate filled with red velvet cake crumbs.

[12] A new song called "Strange Sensation" was written for the film by Alan Menken and his lyric-writer Glenn Slater, while the original score was composed by Mark Mothersbaugh.

[16] According to Deadline Hollywood, test scores for the film were so low that Sony, foreseeing a poor box-office reception, unsuccessfully attempted to sell its distribution rights to Netflix.

[2] In the United States and Canada, the film was released alongside Vice and was projected to gross around $19 million over its first six days.

"[23] On Metacritic, the film has a weighted average score of 24 out of 100, based on 23 critics, indicating "generally unfavorable reviews".

[17] Frank Scheck of The Hollywood Reporter called the film "a Christmas turkey" and wrote, "The overall shoddiness is typical of this feeble sendup that doesn't even manage to be as funny as the recent Benedict Cumberbatch and Robert Downey Jr.

"[25] Ben Kenigsberg of The New York Times found the film dull, writing: "More laughs are all that would have been necessary to prevent the stagnation of Holmes & Watson.

It's cheap and tacky—a bizarrely dated parody of Ritchie's Holmes (complete with a soundalike score) poisoned with rib-elbowing topical references and puerile gags.

"[30] IndieWire reviewer David Ehrlich criticized the script and inability of the film to decide "what kind of dumb it wants to be", giving it a grade of C− and saying that it contained fewer laughs "than the deleted scenes of Step Brothers.

"[31] David Edelstein of Vulture.com wrote "Holmes & Watson begins as ineptly as any comedy I've seen, and then settles into an agreeably silly groove that had the common hordes around me yukking it up.

"[32] Jake Wilson of The Sydney Morning Herald was more positive, writing, "Holmes and Watson is not for everybody, but if you want to see Ferrell off the leash, this is the best opportunity in a long time.