'William Friedken' had created one of the most recognised car chases ever filmed in The French Connection (1971). In this film, for the first time, the car chase has the police chasing the criminals as they both drive on the wrong side of the road, into oncoming traffic.
The car chase sequence took six weeks to shoot. It was the last thing shot - apparently so that, if anything happened to the principal actors, the filmmakers would at least have the bulk of their movie completed without having to replace anybody.
When Masters is visiting Cody in jail, they are talking on phones on either side of what is presumably a clear soundproof wall. Yet after hanging up the phones, Cody says "don't forget about me" to Masters, and Masters answers him as if he heard what he said through the wall.
During the scene when Rick Masters demands his money back from Jeff for the botched hit on Cody in jail, Jeff says "I owe you one Cody". Although some viewers think that the line should read "I owe you one, Rick," Jeff's reference to Cody is not a script error; Jeff is merely saying that he owes Rick "one Cody" - that is, one dead Cody.
Carl Cody: [talking about Max Waxman]
He's a lying son of a bitch! He's probably the motherfucker who did me. He ratted me to the feds. I'll kill him when I get out! I'm gonna give that fuckin' scumbag a serious headache. May God strike me dead if I don't waste him.