Every moment of “Saturday Night” has the vibe of an Aaron Sorkin show: Characters pop up with a new crisis every few minutes, as Michaels power-walks through the halls of NBC as if he were on the set of “The West Wing” or The “SNL”-inspired “Studio 60 on the Sunset Strip.” The energy is infectious.

Jason Reitman assembles a giant, game ensemble for Saturday Night, a SNL origin story that's a little too reverent and tidy.