1.
if your mind flashes back to sth, you remember sth that happened in the past :
Her thoughts flashed back to their wedding day.
—related noun flashback (2)
2.
if a film / movie flashes back to sth, it shows things that happened at an earlier time, for example at an earlier part of sb's life
—related noun flashback (1)
3.
to reply very quickly and/or angrily