An ancient portal hurls Ensign Brad Boimler of Lower Decks back in time to Pike's Enterprise, and Mariner soon follows in a live-action crossover.
In this crossover with Lower Decks, Ensign Brad Boimler of the 24th-century USS Cerritos is examining an ancient portal powered by horonium when it throws him back about 120 years onto Pike's Enterprise. Boimler, starting in animated form, struggles to contain his excitement at meeting his heroes and to avoid changing history. Jack Quaid and Tawny Newsome played Boimler and Mariner in live action.
Orions seize the portal, and Pike trades grain to get it back. The crew's attempt to send Boimler home brings Ensign Beckett Mariner through instead. Boimler realizes that the Enterprise's hull contains horonium, which sends both ensigns home, and the Orions are given credit for the discovery in exchange for peace. Jonathan Frakes directed the episode.