The Winchester brothers would not refer to the storage compartment at the rear of the Impala as the "boot." Harry Potter characters would not use "pissed" to mean "angry" or "upset" and they definitely wouldn't use the phrase "pissed off." I've seen both. Ironically, the Potter example was a BTVS crossover, and the phrase was never used by or applied to the main BTVS character, the only character who could be expected to use "pissed" in that way. Yeah, the third person narrative voice used the phrase.
Anyway, authors not paying attention to the way characters talk can really yank me out of a narrative.
Anyway, authors not paying attention to the way characters talk can really yank me out of a narrative.