(at around 17 mins) During the Brazil chase scene, the time of day appears to change from night to day and back to night again. When the soldiers first enter Bruce's home, it is night and Bruce is thought to be sleeping. However, when Bruce is running through the city, it is clearly daylight, only to turn into night again as he enters the factory.
(at around 57 mins) Just prior to the helicopter explodes, the sky is partly cloudy sky and there is lots of sunlight on the characters. Seconds after the helicopter explodes, the sky is dark and it's pouring rain.
After the cave scene, they somehow get to a motel and Betty has her bag with her, which was nowhere to be seen when Bruce carried her nor in the cave.
An exterior shot of the military helicopter taking Bruce and Betty away after he is captured at the lab, shows it to be a CH-53 or similar variant, heavy-lift Sikorsky S-65 model helicopter with refueling boom. However, the interior is of a much smaller helicopter, more likely a UH-60 Blackhawk or variant.
(at around 1h 11 mins) At the tunnel entrance, when Betty says "Bruce, wake up", he's seen without a baseball cap that suddenly appears after, at most, a split-second cut to her.
Emil Blonsky is supposedly a British officer "seconded" (detached) to the U.S. Army. Foreign officers on detached duty to the American armed forces do not wear American uniforms as Blonsky does in one scene. Only duly enlisted or commissioned members of the U.S. armed forces who have taken an oath of allegiance to the U.S. are allowed to wear the U.S. uniform.
(at around 13 mins) UH-1 Huey helicopter seen early in the film has an "N" registration number. Only US civilian aircraft have "N" registration numbers, US Military aircraft do not.
Given the digestive power of a normal human stomach there is no way that flash drive would survive being in Hulk's stomach for any length of time. Additionally by the time Banner tries to regurgitate it, it would have passed well beyond his stomach.
(at around 1h 35 mins) As Dr. Betty Ross emerges from the side of the crashed helicopter on the roof top, she is seen grabbing onto the barrel of the Gattling Gun. This would be impossible as the temperature of the barrels would to be too hot to touch after being just fired prior to the helicopter crashing.
(at around 1h 35 mins) A tremendous blast of air might temporarily extinguish a blazing fuel-fed fire, but when Hulk clapped his hands to extinguish the helicopter fuel blaze, it didn't remove the fuel and small scattered fires were left burning, which should have rekindled the flames, but didn't.
The actual color of the Brazilian Guaraná drink is amber (similar to beer color) not lemon-green as it is showed in the soda factory where Bruce Banner worked. This is an artistic decision to provide an analogy to Hulk's green color.
Shortly after becoming the Hulk in the factory scene, Banner's trousers are full length, then in the next scene they are knee length shorts. However, it's not inconceivable when a six foot person (Bruce) grows to nine foot (Hulk) while adding huge muscle mass, trousers would appear to be shorts. This is also a recurring image of the comic book.
All pulse monitoring watches, like the one that Bruce is shown wearing requires the large button below the display to be held down for the pulse to appear. Bruce is never touching the watch while it shows his pulse increasing. At best, it would only display the last pulse reading after he had (possibly) removed his finger. This would apply to some heart-rate watches but the Polar F5 uses a wireless sensor strapped around the chest. That watch does not need a finger pressed to it to check the heart rate and will update continuously in monitor mode while exercising.
(at around 57 mins) The heavy downpour after the army gunship crashed, later referenced in the news story, is actually seen off in the distance as it approaches. It may also be a foreshadowing of Thor (2011).
Although General Ross and the soldiers are in the Army, they fly around in Air Force helicopters. As part of U.S. Special operations Command he would have access to USAF SOC equipment.
The Portuguese spoken by some actors acting as Brazilian characters (like Tough Guy Leader) is heavily broken, with ridiculous accents. The Portuguese words and dialog are clearly phonetically memorized. Obviously only Brazilian actors Débora Nascimento and Rickson Gracie speak a real Portuguese.
(at around 44 mins) When General Ross enters a four-digit pass code to enter the deep-freeze storage area, the light on the panel turns green just before he enters the last digit of the code.
The camouflage pattern used by Ross' US Army soldiers is the BDU woodland pattern, which has long been replaced by the digital ACU pattern.
The scenes at Culver supposedly take place in the United States (e.g., USPS mailboxes, etc.) yet the bicycle rack circles say "City of Toronto".
When Banner is supposedly in Chiapas, Mexico, it is clearly Rio de Janeiro, Brazil. At 00:30:44, an orange garbage can with the logo "Prefeitura do Rio" (Rio's City Hall) is seen behind two seated women. About one minute later, Banner is shown sleeping next to a green large door covered with Portuguese graffiti like "paulista" (people born in São Paulo) and "Ja e?" (Rio slang for "let's go?" or "are you in?").
(at around 1h 29 mins) On a New York street a sign of 2 neon discs is clearly seen. This is the famous logo of the Sam the Record Man store located on Yonge street in Toronto.
(at around 39 mins) When Bruce is searching the computer database from the University computer lab, his search for "B* BANNER" fails to find anything. This is not surprising, since the check box titled "Allow Wildcards" is not checked just above the search field, so the search is only looking for a B followed by a literal asterisk.
(at around 31 mins) When Bruce is in Chiapas (Mexico) buying pants he speaks to the lady in Spanish asking for bigger pants, to which she replies "tenho sim". It translates to "yes I do", the only problem is that "tenho sim" is Portuguese, not Spanish.
(at around 12 mins) Despite Bruce Banner warning Dr. Samuel Sterns about the risk of Hulk falling into the wrong hands, he seemed fine sending a blood sample to him via mail (considering the fact that they didn't meet in person at that point).
(at around 8 mins) When the box of drinks containing the contaminated bottle is packaged, it has 'Brasil / U.S.A' printed on the side to show its destination. However, while Brasil is depicted with its Portuguese spelling, the acronym for the United States of America in Portuguese is 'E.U.A.' for Estados Unidos da América, not 'U.S.A.'
Banner jumps from the helicopter to battle Abomination and breaks through the pavement. Betty Ross leans out of the helicopter to try and see him. General Ross pulls her back in. It appears that actress is not Liv Tyler. It may be her stand-in.