“Backwash” is the tale of three slacker friends and the adventures that ensue after they hit the road in an ice cream truck after one of them inadvertently robs $100K from a bank armed only with a large salami. With echoes of the Marx Brothers and Monty Python, “Backwash” is a slapstick look at the effects of sudden wealth on three American losers—Val (Joshua Malina), Jonesy (Michael Panes) and Fleming (Michael Ian Black), told through action, animation, surrealist humor, as well as song and dance