The names of the three main characters are references to characters in Bill & Ted's Excellent Adventure (1989). Lucy Preston and Wyatt Logan have the same last names as Bill Preston and Ted Logan; Rufus Carlin is a nod to Rufus, who was played by George Carlin.
A 2016 lawsuit claims that the series was plagiarized from El ministerio del tiempo (2015) (Ministry of Time), a Spanish series about (in the lawsuit's words) "the adventures of a three-person government team (consisting of one woman and two men) travelling through time to thwart undesired changes to past events". (And in fact the creators of the show were at one point courting Sony to make a US version.) NBC and Sony argue that this premise is sufficiently generic that no individual can claim ownership of it and that otherwise the shows are otherwise entirely different. The case is ongoing.
'Timeless', co-created by Eric Kripke, is one of two new shows for the 2016 fall season that is created by a previous showrunner for Supernatural. The other is Frequency, created by Jeremy Carver. Both shows revolve around Time Travel.