Artistic License: No matter what the film tries to tell you, fire is not a living thing and doesn't react to fear. Also, Real Life arson investigators are much more scientifically rigorous in their work as their findings have to stand up in a court of law.
Real fires tend to involve blinding amounts of smoke that force firefighters to feel around for objects and people with their hands and feet. Real Life firefighters gave this film a pass, though, admitting that a screen full of dark billowing smoke doesn't really make for a visually exciting experience.
None of the firefighters appear to be wearing turnout trousers to protect their legs.
Beauty Is Never Tarnished: Averted with the second probie, Krizminski. He ignores Bull's orders and punches directly into a hot room, triggering another backdraft right in his face. He barely survives, but ends up horribly burned and disfigured.
Big "NO!": Brian when he sees Bull and "Axe" Adcox fall. Adcox hits a barrel on the way down and dies instantly. Bull ends up half-impaled on wreckage; he survives the fall but dies on the way to the hospital.
California Doubling: Mostly averted. All the scenes at Bull's boat were shot on the bank of the Chicago River; the big drawbridge in the background still exists, and operates, in Chicago as of 2013.
Chekhov's Gun: Brian ends up confronting the masked arsonist as he's attempting to flee the scene of a fire that he's set, and in the scuffle, the arsonist suffers an electrical burn. Later on, Brian is able to identify the unmasked arsonist through the same burn mark.
Consulting a Convicted Killer: Brian approaches an imprisoned serial arsonist, Ronald Bartel, when in need of assistance in finding the missing links between a string of recent fires that seem to be connected.
Empathy Doll Shot: Helmet variant - Stephen and Brian's father's helmet is blown clear of the explosion that kills him; a LIFE magazine photographer gets a picture of Brian holding the helmet, right after his father's death.
Energy Beings: Sorta. Both Bartel and Rimgale describe fire as an animal and as a sentient predator as a way to understand how it behaves.
Government Conspiracy: A local one; Swayzak made several backdoor deals with local businessmen (included a forged manpower study) to shut down firehouses across the city and convert them into community centers, with lucrative construction contracts awarded to the conspirators.
Heroic Sacrifice: Stephen and Brian's father sacrifices himself throwing Adcox clear of a gas explosion, setting the plot in motion. Bull's death in a chemical plant, confronting Adcox, is ultimately pointless...but rescuing the mortally wounded Bull finally forces his brother to grow the beard and become a full-fledged firefighter.
Hollywood Fire: Played straight and averted to varying degrees through the movie.
Knight Templar: Adcox. He specifically goes after Swayzak's cronies in the firehouse closing scheme, and sets the fires up so the victims trigger backdrafts; once they explode, they blow themselves out, minimizing risk to firefighters. Unfortunately, in a high rise fire, there was another set of doors that held his backdraft in, and Bull's probie didn't listen...
Mood Whiplash: The opening; Brian as a child goes along to one of his father's responses, an apartment fire that seems mostly smouldering (all smoke). Everything is all upbeat and routine, until his father realizes there's a leaking gas line, and Adcox just released it to the fire. He throws Adcox out of the room just before the explosion consumes him, with Brian watching it all. The photo of him holding his father's burned helmet, looking up at the inferno, follows him right through adulthood (see Old Shame below).
Screw the Rules, I'm Doing What's Right: Stephen is an excellent firefighter, but he has a rather reckless and lax attitude to procedure and the rules, never wearing his mask, never waiting for his hose teams, always going head-on into even the worst blazes, etc.
His reckless attitude rubs off on one of his probationary firefighters with disastrous consequences; the probie is horrifically injured by a backdraft after not checking a door properly, and Adcox and Brian (not unfairly) blame Stephen. Although in light of Adcox being the one who actually set the fire, his condemnation is more than a little hypocritical.
Sleazy Politician: Alderman Swayzak, following a great Chicago tradition; he's preparing to run for mayor, and using firefighters as a political hobbyhorse to ride into higher office.
Sympathetic Murderer: Adcox murdered Swayzak's cronies out of anger that the alderman was gambling with firefighter's lives for monetary and political gain, and to try and save firefighter lives by stopping further closings.
Stunt Double: Partly averted; the end credits actually include the stars among the stunt team.
10-Minute Retirement: Brian, finally driven from Engine 17 into a desk job, rejoins it as a full fledged firefighter after Stephen is killed.
Training from Hell: Stephen singles Brian out through putting him through one of these, and it's implied that he's trying to force Brian to quit. He succeeds at first, as Brian moves to Shadow's investigative office and a desk job. Ultimately, though, Brian grows the beard and rejoins Engine 17 after his brother's death.