From personal experience I remember when a Captain: had to make a go-around on short final because he was high and hot (VMC); wouldn't call "Gear Down" although I'd repeated numerous times "Standing by Gear"; I took immediate control of the a/c because it was apparent (to me) that he was going to land on top of a building approaching MDW (3:00 in the morning)- "apparent" as neither one of us ever confirmed the incident; and he got lost on climb out resulting in non-happy responses from ATC.
There we go, 4 things that I recall. Could have been some others.
From personal experience I remember when a co-pilot: well, I could write a book on this one.
Oh yeh, I remember on occassion a stewardess, oppps, sorry, flight attendant, on occassion would say, "My job's just as important as yours."