In the Season 1 episode “Belly Full of Turkey,” Lily and Marshall visit Marshall’s family in Minnesota for Thanksgiving. All of the men play a dangerous family-invented game called “bask-ice-ball,” but during halftime Marshall comes inside, decked out in his winter gear, to ask how Lily’s doing.
The blooper comes at around 9:34 in a behind-the-scenes video when Jason Segel screws up his line and curses, then apologizes to ABC. The problem? CBS was the show’s network, not ABC. Hannigan catches his error immediately, telling him, “CBS,” with no small amount of incredulity. Everyone around them erupts into laughter and “ooooh’s” before they’re wrangled back into the scene. But before they say their lines, Hannigan says, jokingly, “Should I even do it with him or should we wait for the new guy?” That quip earns her a round of laughs from all the members of Marshall’s very tall family crowded in one small kitchen.
Altogether, it’s an amusing moment from early on in “How I Met Your Mother” history that shows just how new the series was. At that point, Segel didn’t even know what network they were on. Nine seasons and many years later, it’s easy to forget that a lot happened in Season 1 that was pivotal to the show as a whole. Luckily, CBS did not kick Segel off for his mistake!