Oddly enough it's those small differences that really stand out to me, even where they might not between British dialects/accents. "Aluminium"/"Aluminum" or "route" as "root"/"rowt" barely even registers, yet the "a" in something like "pasta" going from being a short sound to more like "parhhsta" (more like "par", the golfing term) sticks out like a sore thumb.