Remember Dune, David Lynch’s less-than-enthralling film version of the influential sci-fi novel by Frank Herbert? Well, try to imagine it starring Mick Jagger, Salvador Dalí, Orson Welles, and David Carradine; with visuals by H.R. Giger, Dan O’Bannon, and Jean “Moebius” Giraud; and music by Pink Floyd. That’s what Alejandro Jodorowsky, the Chilean maker of El Topo, was planning for his own adaptation of the property in 1975. But it fizzled before lift-off. This wonderfully nutty documentary by Frank Pavich sketches in the details of what might have been the trippiest motion picture of all time, with testimony from Jodorowsky himself (still rebellious at 84) and many of his would-be collaborators. Their descriptions are almost as good as seeing the real thing. The epitome of a movie nerd’s pipe dream (90 min.).