Audio problem: Right after Helga is standing behind the "ARNOLD" on the pavement, when she says "Hey Arnold", her lips move as if she's saying it slowly (this is fixed in the 4th season).
Audio problem: The computer's voice says "golf shoes" while the screen says "golf cleates".
Audio problem: When Talbot comes upon the Hulk in his helicopter, the helicopter doesn't make a sound until it appears on screen.
The Raffle - S3-E3
Audio problem: When Kel breaks the TV, the sound is a very clear overdub to make it clear the TV is broken. (00:08:15)
'Unmei no sentaku' mitaina - S1-E6
Audio problem: In front of the vending machine, Hikaru does a little prank with her eyes 'bugging out'. The English dub is fine, but the original Japanese audio has her pronounce an additional line during close-up when her lips are not moving and the mouth is shut. (00:05:40)
Dick and the Other Guy (2) - S3-E23
Audio problem: When Liam is performing karaoke at the end of the episode, his mouth is not even moving for some of the lyrics, and there aren't any vocal tracks on the song, because only the instruments are heard when he abruptly stops singing to admonish the crowd for trying to leave during his performance.