The Big Bang Theory spinoff "Stuart Fails to Save the Universe" recently aired an episode that saw its titular character and companions transported to a live-action Gotham City. The crossover event featured an encounter with Mr. Freeze, portrayed by Eric Allan Kramer, who utilized ice-based attacks. The episode also included a live-action appearance of Jay Garrick's Flash, played by Andy Ridings, who intervened in the conflict.
This unexpected DC crossover generated discussion among fans, particularly the appearance of a live-action Flash, the first such depiction since Ezra Miller's portrayal in the 2023 film "The Flash." The episode also included a narrative nod suggesting that Golden Age Flash might be more suited to fight Captain Cold than Mr. Freeze.
Despite the impact of the Flash and Mr. Freeze team-up, the creators' initial vision for the cameo differed. Co-creator Zak Penn revealed to Deadline that the episode's title, "Spoiler: We Couldn't Get Green Lantern," was indicative of their original plan. The team was informed that a Green Lantern appearance was not feasible due to the ongoing HBO live-action series "Lanterns." Penn explained that the Flash ultimately proved to be a better fit for the story's interdimensional travel theme than Green Lantern would have been.
The decision to avoid Green Lantern characters was made to prevent potential confusion with the "Lanterns" series, which has been noted for its grounded take on the characters. The Big Bang Theory spinoff aimed for a more lighthearted tone.
"Stuart Fails to Save the Universe" is currently in its first season, with its season finale scheduled for next week. The DC Universe's live-action Flash and Mr. Freeze are not currently active in other projects, while "Lanterns" is set to continue its narrative tomorrow, September 20, 2026.