An unused animation for Filia shows Samson ripping open her shirt in anger, revealing her bra while Filia embarrassingly attempts the cover herself up. This was removed from the game because the game developers thought it was needlessly sexual.
During Painwheel's story, Valentine uses the override code 35E-25-40. According to the Skullgirls official website, these are Valentine's measurements.
In some earlier drafts and concept art, Peacock was going to have a more antagonistic role and her personality would have been more "demented" to match. Eventually, her design and character shifted to a more lighthearted tone with a focus on American animation and she became one of the most important protagonists in the game's story.
The use of high-res, hand-drawn art over 3D models was done because the developers simply wanted to, despite the fact it ended up requiring a much higher budget and large team of professional artists and animators.
When Cerebella connects with her Lock n' Load attack, there's a .02% chance of a random, poorly-drawn cat skittering across the stage. An animator sketched a cat in one frame but forgot to take it out, and the development team wished to keep it in as part of an Easter egg.