Rule G.9: There is a 5-point penalty if the first team interrupts a tossup with an incorrect response. A subsequent incorrect interrupt by the second team does not result in another penalty; only one 5-point penalty may occur per question. The second team may still earn 15 points with a sufficiently early signal. Players may earn 15 points on power tossups at any point in the game, including overtime.
What you described is completely possible. A team that leads by 50 points with one tossup left (assuming no pending protests) could still lose if they neg, and the other team vulture-powers, 30s the bonus, and wins in overtime.
FOUR-TIME NATIONAL CHAMPIONSHIP PARTICIPANT
Advisor/coach, Bergen County Academies (NJ)
HSQB forum mod, PACE & HSAPQ member
Formerly played for Washington U. in St. Louis and BCA (NJ).