The creators of hit TV sitcom How I Met Your Mother have apologised after they were accused of causing offence by including a "silly and unabashedly immature" homage to kung fu movies in the show. During an episode of the long-running series, which aired in the U.S. on Monday (13Jan14), Jason Segel's character, Marshall, travels to China to train with three masters in the art of slapping. The masters were played by his co-stars, Josh Radnor, Cobie Smulders and Alyson Hannigan, who were dressed up to look Asian, and the scenes angered a number of viewers, who took to Twitter.com to complain using the hashtag #HowIMetYourRacism. The show's creators Carter Bays and Craig Thomas have now responded by offering up a public apology. In a series of posts on Twitter.com, Bays writes, "Hey guys, sorry this took so long. Craig 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." Thomas added, "I second everything Carter just tweeted - we love all #HIMYM (How I Met Your Mother) fans and apologise that we caused offence." How I Met Your Mother will end its nine-season run on 31 March (14).