"How I Met Your Mother" co-creators Carter Bays and Craig Thomas took to Twitter to apologize for an episode that is being called racist against Asians. Alyson Hannigan, who plays Lily on "How I Met Your Mother," shared their apology on her own Twitter account.

During Monday's episode, "Slapsgiving #3: Slappointment in Slapmarra," Marshall (Jason Segel) learns special kung fu moves in China for his final slap for Barney (Neil Patrick Harris). Marshall's three kung fu teachers were played by Robin (Cobie Smulders), Lily (Alyson Hannigan) and Ted (Josh Radnor). The actors -- all of whom are white -- dressed in Asian-themed costumes and makeup, leading viewers to accuse them of appearing in "yellow face"; Radnor even donned a "Fu Manchu" moustache.

Soon after the episode aired, "#HowIMetYourRacism" started trending on Twitter.

On Wednesday, the creators of "How I Met Your Mother" apologized on Twitter for offending people with the episode. Their tweet was shared on Alyson Hannigan's Twitter yesterday.

Carter Bays wrote on his Twitter: "Hey guys, sorry this took so long. @himymcraig and I want to say a few words about #HowIMetYourRacism. 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. We try to make a show that's universal, that anyone can watch and enjoy. We fell short of that this week, and feel terrible about it. To everyone we offended, I hope we can regain your friendship, and end this series on a note of goodwill. Thanks. @CarterBays @HimymCraig."

Here are what some of "HIMYM" viewers were saying about the episode:

"I used to watch @HowIMetMother but I now refuse to and hope they apologize for yellowface. #HowIMetYourRacism," @suey_park tweeted.

"Besides the gross orientalizing of the women, Ted wore a f---ing Fu Manchu 'stach! Who thought this was ok? @HIMYM-CBS #HowIMetYourRacism," another commented, The Sydney Morning Herald reports.

"Yellowface? Orientalism? Fu Manchu? What?" tweeted one person, CNN reports. "Not okay @cbs."

"Incredibly easy for white people to say 'that wasn't racist,'" another person tweeted. "Not so easy for PoC" -- shorthand for people of color -- "to be marginalized their entire life."