Besides the Cowboy Bebop music on the background, I love how you can hear a muffled "Meet the Sandvich" at the beginning before Kirby busts through the door

Is that an Offspring reference?

That Sakura and Spidey victory one is awesome, and I think it could be easily recolored into their secret character palettes (Armored Spider-man and Dark/Sunburnt/Evil? Sakura).

A reference to Dark/Sunburnt Sakura from MSHVSSF?! YES!