Fairy Friends and Neighbors/Just the Two of Us - S4-E11
Continuity mistake: When we first see Trixie and Timmy inside Timmy's large sand castle (or whatever it was), they were sitting at the ends of a long table. But when Francis destroys the castle, Trixie and Timmy are way closer together.
Answer: That's just decorative. The gas pedal is always on the right and using the left foot would be quite awkward.
Grumpy Scot