The CBS comedy series “How I Met Your Mother” came under fire over an incident in Monday’s episode that some viewers saw as racist, causing the show’s co-creators to issue apologies, Variety reports.

In the episode, titled "Slapsgiving 3: Slappointment in Slapmarra," the problem surfaced during a bit about an ongoing "slap bet" involving the ritual of strong slaps among friends.

"Monday’s episode put the show under fire when Jason Segel’s character continued the slap bet with Neil Patrick Harris’, threatening the ‘slap of a million exploding suns’ that he learned from three masters," the story reports. "The cast’s Alyson Hannigan, Cobie Smulders and Josh Radnor served as said masters, dressed to make them look as though they were Asian.

"Viewers immediately flocked to Twitter to voice their aversion to the use of ‘yellowface,’ and even created the hashtag ‘#HowIMetYourRacism.’ Co-creator Carter Bays responded Wednesday, apologizing for himself and fellow showrunner Craig Thomas.

In a series of tweets, Bays wrote: "With Monday’s episode, we set out to make a silly and unabashedly immature homage to Kung Fu movies, a genre we’ve always loved. But along the way we offended people. We’re deeply sorry, and we’re grateful to everyone who spoke up to make us aware of it."

Thomas added in his own tweet: "I second everything @carterbays just tweeted — we love all #HIMYM fans and apologize that we caused offense."

Bays also said the producers aim to make a show that’s "universal," admitting that they fell short with Monday’s episode.

The series is in its final season, with the finale set to air in March.