Roger Corman rarely made anything worthwhile outside of his Edgar Allan Poe comfort zone. Least of all his comedies. They weren’t funny, just laughable. Like the original Little Shop of Horrors, which is mostly famous for being made in two days in 1960. (And for Jack Nicholson’s gurning turn as a masochist.) But Frank Oz’s film is derived from the 1982 off-Broadway hit, a musical about a man-eating plant made in joyous Rocky Horror mode. It’s an all-round upgrade on Corman’s cult item, with knockout production design, a few sha-boom songs, and well cast leads – Rick Moranis is a perfect klutz, Ellen Greene an adorable dumb blonde, and who’d be a better florist than Vincent Gardenia? Leaving the other guest star cameos in the shade, Steve Martin steals the show as a sadistic dentist, born to be inhumane. In similar vein, The Rocky Horror Picture Show mocks sci-fi B-pic conventions, with added dance steps. Mars Attacks! (ITV4, 9pm Sunday) too has a musical ear, if Tom Jones and Slim Whitman count.