The Riddle of the Sphinx (Inside No. 9) was characterised by Pemberton as a thriller in the style of Anthony Shaffer's 1970 play "Sleuth", while Shearsmith identified the episode as particularly theatrical, in the style of "Sleuth" and Ira Levin's 1978 play "Deathtrap". BBC executives, according to Shearsmith, saw the episode as a cross between "Sleuth" and Willy Russell's 1980 play "Educating Rita" that read as if it had been authored by psychopaths. The executive producer Jon Plowman suggested that the first half of the episode plays out like a radio play. The word-play and tea-drinking in this part of the episode are, in the writers' opinion, very
Willy Wonka Depp as Willy Wonka may be a stone freak, but he is also one of Burton's classic crackpot conjurers, like "Beetlejuice" or "Ed Wood"." Mick LaSalle from the "San Francisco Chronicle" found that "all the laughs [in the film] come from Depp, who gives Willy the mannerisms of a classic Hollywood diva". Roger Ebert wrote "Depp, an actor of considerable gifts, has never been afraid to take a chance, but this time he takes the wrong one. His Willy Wonka is an enigma in an otherwise mostly delightful movie from Tim Burton," while Peter Travers wrote in "Rolling Stone" magazine