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".
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 Soup for the Soul - S6-E16
Audio problem: When Tommy is talking about how he recruited Sally to help him get into the fraternity, but has gone mad with power, at one point it switches to a wide shot and you can see his mouth isn't moving. (00:19:28)