Continuity mistake: When Bruce Banner is submerged in the holding tank at the desert lab, he has hair on his chest. But when he changed back from the Hulk at Betty's cabin, his chest was smooth.
Continuity mistake: When Betty takes Bruce back to his childhood home, she sits on a swing prior to entering the house. The swing is moving as the go into the building but is stationery a few moments later (it wouldn't have had time to come to a complete standstill).
Revealing mistake: When Hulk rips the turret off the tank and swings it around in the desert has a solid base. This is correct for a model but not for a real tank which has a hollow turret for the tank captain to stand up from the bottom of the tank through the turret and look out the top.
Continuity mistake: When Betty walks down the stairs to calm the Hulk down the camera angle from the front shows her hair blowing in the wind, but the camera angle from the back doesn't.
Answer: That is an altered version of Eric Bana's voice.