I’ll give “The Continental” this: of all the reasons the “John Wick” prequel frustrates, underwhelms and disappoints, the involvement of Mel Gibson barely manages to rank. That, at least, is a major accomplishment. The three-part series, subtitled “From the World of John Wick,” was anticipated by a steady stream of red flags: a gap of more than half a decade between the official greenlight and Wednesday’s premiere; the move from Starz, a network owned by franchise studio Lionsgate, to Peacock; the news that Chad Stahelski, the stunt performer turned action auteur, would not direct any episodes, though he retains an...