The entire Continuity Nod given to Lei-Fang's ending from #4 at the end of her Story Mode chapter in #5, given a twist at the end.
During Mila's Story Mode chapter in #5, she's at work at the diner when Brad orders a drink. Mila gets sidetracked and leaves early to spar with Tina. Brad follows her to the gym and asks what's taking her so long to get his drink.
Sarah's introduction video.
Tina immediately seeing through Bass's Paper-Thin Disguise during the 5th tournament, followed by what she does after her fight against him.
Brad and Eliot fighting over the last piece of food. Also a Crowning Moment of Awesome for both of them. The icing on the cake? The monkey steals it from both them.
Eliot in Taylor's Bar with Christie.
*camera on Eliot's eyes looking at Christie's boobs*
Zack's various antics while trying to recuit the cast into the 5'th DOA Tournament, which include:
Getting beaten up by Tina and getting left knocked out on the ground. Made more funny during his storyline, where his beating by Tina is shrouded by a black screen, and then some time later, Brad trips over him.
His mistaking Sarah for Tina, then getting put into a sleeper hold by the latter for it.
Shooting out of a cannon while Hitomi and Leifang are training in a circus area, and he crash-lands into a prop. Even his speaking lines are ridiculous: