The scene where Barry is lying dead next to Frank, in the original theatrical release, Leo said to Frank, "People will be eating them for lunch tomorrow in their McDonald's hamburgers and not know it." When the film came out on VHS, "McDonald's" had been removed and only "... tomorrow in their hamburgers and not know it" can be heard. On DVD, "Whimpy burgers" is now said by Leo.
The burglary tools used throughout the film (such as the hydraulic drill used in the opening sequence) were not props, but actual tools which the actors were trained to use. The tools were supplied by actual thieves who served as technical consultants on the film, principally John Santucci, who also portrays Sgt. Urizzi on screen.
The vault which James Caan's character breaks into in the opening scene was a real vault, purchased at a cost of $10,000, specifically so that Caan could break into it, using the tools and techniques supplied by John Santucci. Every crew member was armed with a fire extinguisher in case of a blaze from the intense heat of the thermal lance. Caan later remarked that although many elements of John Santucci found their way into the character of Frank, he resisted doing a straight impersonation of the boisterous Santucci.
The screenplay for this film was adapted from the novel "The Home Invaders", written by Frank Hohimer, himself a professional thief. Hohimer was serving time in prison at the time this film was in production.
When Frank tries to light his cigarette in the diner scene, the lighter does not work. This was not scripted. The prison story that Frank tells in his monologue is based on a letter Michael Mann received from a real inmate.
Contains similar elements, lingo, and themes with Mann's Heat. It's worth mentioning, that on the commentary with Caan and Mann, Caan reveals that Mann is currently working on a film with Pacino and De Niro which is Heat.
The house that was "severely damage" in the explosion was demolished and three smaller homes were built on the property. Apparently the explosive charge was too large for the job as it caused a fire and cracked the home's foundation.
[Cops & Robbers]
Many real-life Chicago criminals and police officers served as advisors to director Michael Mann, and Mann cast many of them on screen, often in contradictory roles (i.e. former Chicago police officers Dennis Farina and Nick Nickeas appear as criminal henchmen, while former professional thief John Santucci appears as a police officer).
The house that was blown up was actually a fake structure in front of the real house; nevertheless, when it blew up it heavily damaged the real house behind it. The residents and neighbors were moved to a hotel during filming.