Pifias

When Detective Bloom describes the killing in the hotel, Jimmy the Gopher hears the story from inside the panic room, though in the beginning of the film Gorgeous George had to push the intercom button to talk from outside, which did not happen during Bloom's explanation.

When the brothers are cutting their hair and showering, Connor's tattoo is the top half of Jesus and Murphy's is the bottom half. But during the tattooing scene on the boat their tattoos switch briefly until the meeting with Romeo.

When Noah is dragging one of his victims to a pit in a flashback, he clearly doesn't have a tattoo on his right hand.

After Noah and the Roman have their conversation, the Roman starts the record again, setting the needle about one half inch from the edge. After the following gun fight the record player winds down to a stop, and the needle is at the beginning of the record again.

When Rocco and the brothers are in the ice rink, you can see Greenly skate past in the background before it cuts to Connor.

When Bloom tells how the shoot out went in the Mob boss' room, she is not holding down the talk button. A BIG production is made earlier in the film that if you don't do that, those IN the panic room cannot hear you. Therefore the last mob member could not have "listened to her tell what happened".

During the shootout at the Prudential when Conner and Murphy are sliding across the floor while shooting, they fire at least 15 rounds from each of their pistols. However these new pistols of theirs, which are supposed to be Desert Eagle Mark XIX's chambered in .50 AE (though the actual guns used are .357 Magnum Desert Eagles, but the script ID's them as .50 caliber Desert Eagles). The Desert Eagle .50 AE has a magazine capacity of 7 rounds, so Conner and Murphy's pistols would hold a maximum of 8 rounds (7 in the magazine plus an extra round in the chamber), though in the elevator they are shown racking the slide and chambering a round after putting the magazines in, so they most likely only had 7 rounds in each gun. It would have been better for them to keep their Berettas since they hold a maximum of 16 rounds, 15+1 in chamber, it doesn't make sense for them to switch them for pistols that have half the magazine capacity of their old pistols right before attacking a room full of mobsters armed to the teeth.

Near the very beginning of the film, Romeo, played by actor Clifton Collins, Jr., infers that Tabasco sauce was invented by Mexican people. This is not true. Although the name comes from the Mexican state of Tabasco, the sauce is a U.S. product produced by the McIlhenny Company of Avery Island, Louisiana.

The script stated that the desert eagles used by the saints were chambered in 50 AE. However the guns used in the films had fluted barrels, something the 50 caliber version wouldn't have.

Romeo's 1911s were fitted with suppressors, despite not having threaded barrels.

When Gorgeous George goes into the hotel room at the Prudential, one of the mobsters says, "Jimmy the Gofer, la cortina" (the curtain). "La cortina" means "the curtain" in both Italian and Spanish.

Around 23 minutes (:23), Romeo says, "This ain't rocket surgery"; inferring something is not difficult. However, he got his expressions crossed up. It's either "Brain surgery" or (the more common), "Rocket Science".

When the Roman starts the record playing, the music begins before the needle touches the record, and continues while the needle is in the outside band where there is no sound. The music continues to play as the scene shifts, and the needle suddenly is in the middle of the record.

When Eunice has her pistol in Gorgeous George's face, you hear her cocking the hammer. The pistol is a Para LDA and is double action only. You cannot cock the hammer. In fact the very next scene, the hammer is still down.

In the final tête-à-tête between Il Duce and The Roman in the garden atrium, there are occasional reflections of a little blue-green monitor in each lens of each character's sunglasses, likely a dialogue teleprompter.

During the shootout replay at the bar, with Eunice walking down the middle of the mobsters, you can see the blood packs behind several of the guys' shirts and the mini-explosions that go off when they are triggered.

When the wings of the angel statue fall off during the shoot out at Louie's house, you can see the cable holding the wing on the right.

Yakavetta's hideout is said to be in the Prudential Tower. The Pru is a 52-story skyscraper made mostly of glass that says "PRUDENTIAL" on the top, not a white concrete building.

While explaining what happened during the prudential shootout, Agent Bloom and Romeo interact with each other after Romeo's attempt at a one-liner. Yet, Bloom wasn't there for the shootout, and only showed up to narrate the flashback.

In the opening crime scene, S.A. Bloom suggests that the perp was short because the exit wounds were lower on the face than that of the "Saints", however, (in that scenario) someone taller would most likely have a downward trajectory while a shorter person would aim more level, thus resulting in higher exit wounds.

After the forklift incident when the brothers say their prayer and then cross themselves, they go in the incorrect order. The correct order is: head, middle, left shoulder, right shoulder, but the brothers switch the right and left shoulder.

During the meeting of the Dons, Yakavetta states that the Saints killed his father, then goes on to say "mi Padrino" which means my godfather. Clearly a contradiction, as a son would never refer to his father as "godfather" even within the "families".

Bloom planned on disguising the MacManus' shootout in the bar as a shootout between the gangsters. However forensics would have picked up that the bullets found in the dead bodies didn't match the guns they planted in the corpses hands.