Having only ever flown the 330 it is a bit hard to compare, but there are a few clues from this that should have warned the crew that something was amiss. The Flex temp of 74 degrees should have been one of them.
Some 13 odd years ago departing from Istanbul LTBA on a warm summer's day, I mistakenly entered 43 deg. C as our assumed temperature instead of 34 deg. C. It was at almost our maximum AGTOW and my skipper asked me to take off my " shiny metal wings and flush it down the toilet! " He rightly shouted at me at that at almost max AGTOW, a high assumed temperature should have raised red flags. YMML has a much longer runway but an assumed temperature of flex of 74 is glaring red flag. " Contagious " fatigue aside, I guessed the crew must have been really distracted by something else as not to have noticed.