From my own list...
Forgetting at least one of the hop additions
Did I add the Irish Moss?
Anybody know where the bumblebee (the flying, stinging kind) went?
Running out LP with 30 minutes left
Oh look! Maple leaves floating in the boil, again.
The list can go on and on. And every one turned out fine. 8^)
Don't let yourself get too distracted and you'll be fine.