The same Porsche which gets collected from the parking house, appears earlier on in the movie, about 22min into the movie. Actually - it is the same scene in which Nolte and Murphy chase the Porsche for a few seconds.
Ganz catches Jack's 6-shooter, and then fires 8 shots without reloading.
Reggie is handcuffed when Jack throws him into his car after getting him out of prison. In the next shot, Reggie's left arm is stretched out along the back of the seat and his right arm is hanging out the window. In the following shot, he is handcuffed again.
When Reggie takes the knife from the redneck, he closes it and places it on the bar with his right hand before breaking the glasses and being told where Billy Bear's girlfriend lives. When he turns around and talks to the people in the club, the knife is clearly still on the bar. He then walks out to the street where he takes it from his back left pocket and gives it to Cates.
Thirty minutes in, Jack and Reggie are driving to get Luther. Luther is visible a few car lengths ahead of them, driving Reggie's car. The car wasn't even picked up from storage until much later in the movie. It's the same scene used when they're tailing Luther about an hour into the film.
Cates would have easily been fired for giving up his gun to Ganz in the hotel, allowing Ganz to then kill a second police officer, Al. Police officers are trained never to do that.
While trying to get Reggie's attention in his cell, he yells into his walkman causing feedback. That's not something that can be done with a walkman.
When listing the soundtrack in the closing credits, the song Roxanne is credited as written by S. Sting, rather than Sting.
Jack would have been suspended pending a disciplinary review for surrendering his weapon and allowing Ganz to use it to kill his partner and another cop later on. He wouldn't have been able to retrieve Reggie from jail and he certainly wouldn't have been on the streets working.
It would go completely against police training for an armed Cates to merely hit Ganz as he, while also armed, approaches the hotel lobby--especially after Ganz had already killed a police officer just moments earlier. Cates' training would have required him to shoot Ganz on sight.
When the receptionist at the hotel calls her friend, she uses touch-tone direct dialing. Later when Cates tells her to call for help, she tries to place a call using an operator when clearly she could've just dialed 911. While this is true, 911 was first instituted in San Francisco only the year before, in 1981. Thus, it is very conceivable that the receptionist either was not aware of 911 or, amid the panic from the situation, instinctively tried the operator out of habit.
When Billy busts Ganz out of prison, the guard says on the radio "two fugitives", which is an accurate description for anyone who flees.
When Jack tears out of the gas station, Reggie falls into the back seat. In the next shot, as they round a corner, Reggie is sitting up in the front seat. But there is no way of knowing how long it has been since Jack drove off.
When Henry Wong's dead body is shown leaning down sideways on the park bench, his forehead has a small-caliber bullet hole but no trace of the blood that would have gushed out from his brain if he had died from that wound and immediately fallen over. But it's possible he died from other wounds, and was left upright long enough for his blood pressure to drop before being laid down.
The red station wagon that swerves to miss Cates' car as he backs out to follow Luther in Reggie's car is the same one that Billy & Ganz pulled Luther & Rosie into earlier in the film.
Obvious stunt double for Reggie (John Sherrod) seen in some shots during his fight in the alley with Jack.
Reggie is supposedly singing along to "Roxanne" in his jail cell, yet he gets some of the lyrics out of order, which wouldn't happen if he was actually listening to it.
Once the two police detectives were killed the entire police force would be working around the clock to find their killers. One detective (Cates) would not have been doing it alone.
Upon meeting Reggie, Cates says he wants to talk to him in private but takes him just outside his cell and talks loudly enough to create an echo, where it would be only easier for other inmates to hear him.
The movie is titled "48 Hours". Jack and Reggie are up/awake for the entire time ( with Jack up even longer), chasing down Ganz and Billy, but neither one of them show any sign of fatigue or sleep deprivation; and neither one of them show signs of stubble/beard growth in those 48 hours.
(at around 1h 8 mins) We're in Vroman's bar, an up-tempo group bringing it on. We can hear a piano (conventional, vs. a keyboard) player going at it, but when we get a shot from behind the piano player, he's moving his body up and down as if he's "into it" and playing, but in looking at his hands, he's barely flinching, and he's certainly not playing it.
While looking for Luther, Jack and Reggie visit an apartment in The Mission and learn they should look for their quarry "just around the corner in Chinatown." In reality the Mission is 3 miles from Chinatown.
After the fight between Cates and Reggie, the police inform them that the two women called the police on them. That move would be totally counterproductive since Cates and Reggie openly believed their story and left; their action would only suggest they had something to hide.
During the subway shootout, Reggie tells Cates, "I'm going after the money," and begins to chase after Luther, but that item goes completely unresolved. While it is implied later that Reggie followed Luther in order to know where he was staying and be there for the exchange, he had no way of knowing the incident with Ganz would end the way it did...with Ganz getting away.
During the hotel shootout, though he is armed, Cates chooses to knock Ganz to the floor instead of shooting him, which is an absolutely pointless move that is completely out of step with police training.
During the "class isn't something you buy" scene when Jack & Reggie are following Luther, Jack says to Reggie class isn't something you buy and then says "...look at you, you've got a 500 dollar suit on and your still a lowlife." But earlier in the film when Reggie is first released and is wearing the suit he tells Jack that it was a $900.00 suit which Jack should have known later in the film.
When Ganz and Billy Bear take Rosie from Luther, Luther tells them that he can't get the money until Monday, that the place they have it hidden didn't open until then. Ganz then tells Luther that they're keeping her until he gets them the money. Billy Bear broke Ganz out of
prison, killing two guards in the process, then killed their old partner (Wong) all to get the money that was hidden. There's no way Ganz would've let Luther walk away without making him reveal where the money was hidden so he could decide whether to get it himself or not, rather than waiting until Monday.