As I mentioned two years ago, the TWOK department colour scheme wasn't followed that faithfully on screen, and you can frequently spot characters wearing the wrong uniform. Scotty, in particular, seems to swap back and forth between engineering yellow and command white for no apparent reason.
Scott switches from red (engineering in TMP) to yellow (engineering in ST II) to white (as "Captain of Engineering" of the Excelsior in ST III).
The worst costuming mismatch was in ST VI: Valeris's collar colour not matching her shoulder strap. There was no budget to make more pieces, so they simply found bits that fitted the actor.