Darkness and Light: Part 1 - S1-E11
Other mistake: When the Outcasts are launching boulders at the helicopters, they hit one that explodes immediately, and both occupants can be seen emerging from the fireball, safely parachuting to the ground. Even if they were able to jump from the helicopter before it exploded, their proximity to the explosion would have killed them before they had the chance to deploy their parachutes.
Darkness and Light: Part 1 - S1-E11
Other mistake: The river that Hulk battles Doc Samson in is only ankle-deep, but when Samson knocks Hulk out with the sonic gun, the river current is able to carry Hulk downstream. Hulk is lying flat on his back, and since the water is only ankle-deep, his back would be touching the floor of the river. In this case, the current of a shallow river would not be able to carry someone of the Hulk's mass.
Other mistake: When the forklift driver gets distracted by She-Hulk and crashes into the stack of metal vials full of flammable liquid, Bruce and She-Hulk don't hear any of the commotion until the explosion happens, even though they are only a few yards away. The crash and the falling metal vials should have been loud enough to alert them.
Other mistake: When Bruce Banner is attempting to rescue the nun from the fire, a beam falls from the ceiling and hits him in the head, triggering his transformation into the Hulk. Just before he starts his transformation, a set of green glowing eyes appear above his head. It appears the animators didn't properly sync the glowing eyes onto Banner's face.
Other mistake: This show is in the same continuity as the Fantastic Four series from around the same time. However, in Fantastic Four, Dr. Doom has a German accent, and in this episode, he has a slight British accent.
Other mistake: When Betty is going over the plans to infiltrate Sea-Base, she mentions they have to go ten floors down. When we see the base, it is nowhere near tall enough to be ten floors.
Other mistake: When the Leader and his minions are escaping to the rooftop, the bomb detonator says there are only 30 seconds left. After Leader escapes and Hulk goes back into the building to get the bomb, the detonator says 10 seconds remain. While there is an argument to be made in movies and television not being strict with real time, in this instance, far too much happened onscreen for only 20 seconds to have passed. The heroes confronted the villains, one villain tried to talk a hero into coming with them, the police arrive on the scene, a battle happens on the rooftop, the villains escape with the police in pursuit, etc.
And the Wind Cries... Wendigo - S1-E10
Other mistake: When General Ross is telling Hulk he will take care of Betty, he tells the Hulk he needs him to take care of the Wendigo. At this point in the episode, Ross doesn't know that the Wendigo is the creature that they are hunting.
Other mistake: When Bruce Banner is sitting on the dock and recording his thoughts on a tape recorder, you can see that while his reflection's mouth is moving, his actual jaw is not.
Other mistake: When the Hulk takes down the S.H.I.E.L.D. helicopter, it is shown crashing to the ground with its pilot parachuting to the ground shortly after. However, the pilot was never seen ejecting and the helicopter's cockpit door was still closed when it crashed to the ground.
Man to Man, Beast to Beast - S1-E6
Other mistake: When Banner snatches the tape recorder out of Langkowski's hands, the recorder stops playing without Banner pressing any of the buttons.
The Return of the Beast: Part 2 - S1-E2
Other mistake: After the Abomination abducts Bruce Banner from the cavern, he causes a complete cave-in at the entrance. When Rick and Betty come to, they are able to see perfectly fine despite the sun being completely blocked out. Rick even states when he and Betty start to remove all the rocks that are blocking the opening that they need to find some blue sky before they can find Bruce.
The Return of the Beast: Part 1 - S1-E1
Other mistake: When Talbot is grilling Banner for his relationship with Betty, when Banner is saying "Someone like you perhaps," the screen briefly constricts and then expands back to normal size, similar to a window on a computer screen being maximized.