Filming isn't linear in time, especially for the car-building shows.
If you scan the backgrounds, you see cars from past episodes, future episodes, and in various stages of completion.
Sometimes, the subject vehicle can be seen in various stages as though the work has gone backwards.
Film time - meaning, cameras & crew & filming - is very expensive, so things are pretty much shot-gunned and edited later by topic/build/repair.
That explains how SOME of the drop-in cuts/edits can have inaccurate dialog or seem out of place - those are obviously shot at a different time.