There are multiple references to Doctor Who through the whole series. Nathan Ford's aliases are all names of actors who portrayed The Doctor. Additionally, Hardison wears a bow tie during season five, and when questioned, says "Bow ties are cool." During "The Frame Up Job", Sophie and Nathan introduce themselves as Agents Tennant and Smith.
Though seasons two through four were set in Boston, filming was actually done in Portland, Oregon. In "The Three Strikes Job", when Eliot (Christian Kane) is impersonating a baseball player, he makes a reference to having played in Portland. Moreover, the ballpark they are stealing, PGE Park, and the Beavers, are in fact Portland's baseball team. In season five, the Leverage team finally makes their move to Portland in the show, as they film there anyway.
Parker (Beth Riesgraf) is named after the famous fictional conman Parker, created by Donald E. Westlake, under the pen name Richard Stark. Just as in the novels, Parker is only ever referred to as "Parker". No first (or possibly last) name is ever given, though both the Leverage character, and the one from the novels, is known by many aliases.
In "The 10 li'l Grifters Job", Nate (Timothy Hutton) dresses up as Ellery Queen, and says he was "the world's greatest detective". Timothy Hutton's real-life father, the late Jim Hutton, played the title character in the "whodunit" show Ellery Queen (1975).
Richard Chamberlain is in two episodes as the character Archie Leach. That is also the name of the character played by John Cleese in A Fish Called Wanda (1988). Cary Grant's birth name was Archibald Alexander Leach.
Aldis Hodge and Christian Kane played roles in versions of Friday Night Lights. Christian Kane played Brian in the movie, while Aldis had a small role in the television series for six episodes, as Ray "Voodoo" Tatum.
The Leverage team often encounters a specific safe, The Glenn-Reider. In The Librarians (2014), which is also produced by Dean Devlin, in the episode, "And The Point Of Salvation", the same safe company is mentioned.
While the character of "Parker" in this show, is a tribute to the Donald Westlake character, somewhat more faithful versions of Parker have been played by Lee Marvin (Walker in Point Blank (1967)), Mel Gibson (Porter in Payback (1999)), and Jason Statham (Parker in Parker (2013)), among others.
Kari Matchett, who plays Nate's ex-wife in several episodes, and Saul Rubinek, who played Victor Dubenich in "The Nigerian Job" and "The Last Dam Job", and James Tolkan (The Cross My Heart Job) also had roles in the television series A Nero Wolfe Mystery (2000), for which Timothy Hutton was an Executive Producer, and in which he was a co-star. Kari played the girlfriend (Lily Rowan) of Timothy Hutton's character Archie Goodwin, along with some other roles in this repertory-company type series. James Tolkan was also part of this company, and appeared in many episodes. Saul had a recurring role (as Lon Cohen), and also appeared with Hutton in the television movie The Golden Spiders: A Nero Wolfe Mystery (2000) (as Saul Panzer).