One Night Only takes place in a world where single people are only legally allowed to have sex on one night per year. Add to Google settingsAnother thing kept secret in the trailer? The numerous cameos in One Night Only. The trailer mostly focuses on stars Monica Barbaro, who plays Allie, and Callum Turner, who plays Owen. But from pictures of famous stars briefly appearing on screen to actors showing up as themselves, the cameos just keep coming in this comedy.