Part of airmanship is managing distractions and maintaining priorities sometimes by adjusting what can be adjusted (delaying a checklist, telling someone to stby, etc) as necessary. It's what we do.
Clearly it doesn't always work and like everyone else I'm interested to see the report with probable cause.
When taxiing in the dark, what sort of view does the aircraft lights give of what's off to the side of the taxiway in front? Or does it pretty much just show the area immediately in front of the aircraft (especially high up in a 747). Also, from how far away are the red runway signs visible, especially in the presence of other lighting? It looks very small and low down in that picture.