The first Parker film since author Donald E. Westlake's death in 2008. Westlake is credited under his famous pseudonym Richard Stark, which he wrote all of the Parker novels under.
Parker calls his girlfriend and her phone displays a caller ID of (504) 723-2343, which, when Googled, is the phone number of a Louisiana film crew person with the last name of Parker (who doesn't appear to have worked on this movie).
While showing Parker a mansion in Palm Beach, Leslie inquires if he's married, and Parker tells her that his wife passed away. While Parker could be lying as part of his alias, this could be a reference to the first Parker novel "The Hunter" where Parker's wife commits suicide after he returns from being betrayed and left for dead by his wife and partner. "The Hunter" was previously adapted in John Boorman's Point Blank with Lee Marvin and Brian Helgeland's Payback with Mel Gibson.
Palm Beach County Sheriff's Deputy wears the proper PBCSO uniform but his badge is from the West Palm Beach Police Department and not the County issued PBCSO larger Star badge.
Parker steals a blued M1911-type pistol from the hunters' motel room and it ends up in his duffel bag. Later, the blued M1911 has been replaced by a nickel-plated M1911, Ross's "best .45" from later in the film.
When Parker slides under the garage door as it is closing (twice) at Melander's house, he would have broken the infra red safety beam, so the door should have stopped and re-opened, alerting Mr. Rodrigo and his gang.
Leslie Rodgers: I'm sick of chauffeuring these fucking entitled wannabe playboys who have never worked a day in their life. Showing them houses that I could never afford. Laughing at their jokes that I can't stand. All while fending off their gropes. But not all their gropes. Because you never know, one of these days I might just might get a full commission.