[10] He was noticed by Sarah Jessica Parker[11] and shortly after he made several television guest-star appearances including Sex and the City, Felicity, and Law & Order: Special Victims Unit.Cahill was also a recurring guest-star in the NBC sitcom Friends as Rachel's young assistant and boyfriend, Tag Jones.[12] In the 2004 hockey movie Miracle, Cahill had the chance to play his boyhood hero, goalie Jim Craig.[18] He was in Tom Donaghy's one-act play, I Need a Quote, about "a hilarious telephone conversation between a single mother and a home insurance salesman."[19] In the summer of 2012 Cahill performed in David Adjmi's play, 3C, at the Rattlestick Playwrights Theater in New York City.