McElhenney claims that 50 weeks of each year are consumed by acting, producing, and writing for the show, but he did find time to appear in the third season of "Lost" in the episode "Not in Portland". This was a result of McElhenney meeting "Lost" co-creator and executive producer Damon Lindelof, who is a fan of "It's Always Sunny in Philadelphia". McElhenney continued the role in "Lost", featured again in the sixth season for a single episode. McElhenney is a fan of "Game of Thrones" and was thrilled that the series' writers, David Benioff and D.B. Weiss, asked to write an episode of "It's Always Sunny". He and his co-producers accepted the offer, resulting in the Season 9 episode "Flowers for Charlie" in 2013. In 2019, McElhenney made a cameo appearance as an extra in the Season 8 premiere episode "Winterfell".