A Case of Dairy-Uh / Lights, Camera, Adam - S3-E13
Factual error: The man that Vicky has a crush on (or something like that) drinks his tea, but the level doesn't go down.
The Big Scoop / Pipe Down - S3-E10
Factual error: After Timmy makes his wish of having no sound, and he finally wakes up, the clock said 7:42 (before we see Timmy waking up), but when he walks there, it read 7:43, then jumped to 7:44 on the same shot.
Information Stupor Highway - S3-E1
Continuity mistake: When Timmy, Mom, and Dad are writing the love letter to Trixie, what they are typing doesn't match with what their writing.
Answer: That's just decorative. The gas pedal is always on the right and using the left foot would be quite awkward.
Grumpy Scot