Continuity mistake: When Jennifer Walters is first introduced, her fingernails are unpolished. Later when she is restrained in Dr. Doom's lair, her fingernails alternate between being painted pink and red. Given that she and Bruce were running for their lives, she wouldn't have had time to paint her nails. Later when she transforms into She-Hulk, her fingernails turn green with the rest of her body, but if her fingernails were painted, they should still appear that color, as her skin and hair turning green wouldn't magically remove nail polish.
The Return of the Beast: Part 1 - S1-E1
Continuity mistake: When Banner is strapped to the chair and trying to resist transforming into the Hulk, the extent to how much he has transformed varies. Some shots will show his hands and head becoming larger, and the next shot will show him to instantly be back to normal proportions.
Continuity mistake: When General Ross reappears at the end, he is standing directly behind Gabe Jones. A couple of shots later, he is now several feet to Gabe's left. (00:20:22)
Continuity mistake: When Betty and Gabe Jones are talking in the end, there is a brick wall in the immediate background. A few shots later when Betty greets her father, the wall is nowhere to be seen and the room is considerably deeper. (00:20:15)
Continuity mistake: When Gabe Jones is requesting backup, in the wide shot, his brown hair is more golden in color. (00:14:45)
Continuity mistake: When Bruce is rappelling down the shaft, at one point he turns his body face down, and you can tell by the rate at which the background is passing by that he is instantly going slower than the previous shot. If anything, his speed should have increased since he's no longer in a position to slow his descent by using his hands to rub against the rope.
Continuity mistake: When She-Hulk is suggesting she and Bruce go to Rodeo to go shopping, they leave footprints in the sand. When the camera angle changes to a wide aerial shot, their footprints have disappeared. (00:21:14)
Continuity mistake: When the director spits the contract out, it flies up in the air and then falls back to the ground. When the shot changes and he says "It always goes right to their heads," the contract falls from above and bounces off his head.
Continuity mistake: Just before She-Hulk shoves the contract in the director's mouth, the clip at the top of it changes from black to white. (00:20:57)
Continuity mistake: When She-Hulk is hang-gliding towards the Hollywood sign, you can see the letter Y is unoccupied. When the shot changes, Hulk is suddenly sitting there. The font style of the letter Y also changes. (00:08:47)
Continuity mistake: When Hulk throws the robot at Dr. Doom, you can only see a green background behind Doom. When Doom gets back up, you can see a rock wall behind him. (00:04:42)
Continuity mistake: When Dr. Doom first walks into the lab, his mouth is open. When the shot changes, his mouth is suddenly closed.
Continuity mistake: When She-Hulk and Betty begin climbing up the elevator shaft, at first they are climbing up rope. When the shot changes, the rope now has the appearance of elevator cables. (00:15:14)
Continuity mistake: When the model removes the building schematic from the circuit breaker door, the schematic is suddenly drastically smaller when the shot changes. (00:14:56)
Continuity mistake: A handle appears on the door of the laundry chute that the models use to escape the dressing room. (00:11:42 - 00:12:23)
Continuity mistake: When Gargoyle is saying "Seal the doors," his left eye is bulging while his right eye is normal size. It's supposed to be the other way around. (00:09:30)
Continuity mistake: When She-Hulk and Bruce's limo is approaching the building, you can see the car slowing to a stop. When the shot changes to inside the limo, you can tell by the light glares passing by the window behind Bruce that the limo is now moving faster.
They Call Me Mr. Fixit - S2-E4
Continuity mistake: When She-Hulk enters Miss Allure's highrise by scaling the building and coming through the window, the window is instantly closed again when she confronts Miss Allure (note the glare on the window just over She-Hulk's right shoulder). (00:19:39)
They Call Me Mr. Fixit - S2-E4
Continuity mistake: After Miss Allure fails to hypnotize She-Hulk, the white of She-Hulk's eyes are briefly colored green. (00:20:02)
They Call Me Mr. Fixit - S2-E4
Continuity mistake: When Crusher Creel first finds Banner in the building wreckage, Crusher is shirtless. When the shot changes, Crusher is suddenly wearing the tattered remains of his suit jacket. (00:17:42)
Answer: The Hulk is a giant brute who smashes everything in his path when he is angry. In Ang Lee's "Hulk," General Ross, played by Sam Elliot, explains it to his daughter.