As one of the producers, Mark Wahlberg offered the role of Billy Taggart to Michael Fassbender, but when he declined, Wahlberg ended up playing the part himself.
When Billy is getting into Katy's car he asks her, "Where did you get these seat covers, the Gaza Strip?". Katy is played by Alona Tal who was born in Israel and served in the Israeli Defense Forces.
When Billy and the mayor are in the mayor's office where he first hires Billy to investigate his wife, the decanter and the glasses on the table and the blanket on one of the couches all change position repeatedly between shots.
In Jack Valliant's elections headquarters there's a poster with the Hebrew word for "Jewish". Though those are the correct letters of the word, they're written left to right instead of right to left (hsiwej).