Mockumentaries can be really enjoyable when they're executed well, and there are plenty of examples like “Zelig,” “This Is Spinal Tap,” and “Fear of a Black Hat” that prove it. However, this new film from writer-directors Nick Lieberman and Molly Gordon doesn’t quite manage to achieve that same level of success. The movie is inconsistent—at times it shines with genuine humor, particularly toward the end; but at other…

During a seizure triggered by the flashing lights (or possibly the singing) at a local amateur production of "Bye Bye Birdie," Joan (played by Amy Sedaris) is incapacitated, leaving her opportunistic and not particularly intelligent son, Troy (Jimmy Tatro, who resembles Channing Tatum), responsible for her summer theater camp. The camp’s functionality relies heavily on Amos (Ben Platt), Rebecca-Diane (Molly Gordon), …