The flavor text for checking Noelle's bed in Queen's Mansion changes depending on if you retained the Bed Inspector title (by checking every bed in Castle Town and not getting the moss in Cyber City) or not.
If you try to go back to the roller coaster in Cyber Field after visiting Queen's Mansion for the first time, a new Werewire NPC and a new slide will appear in the room before it.
Posting my deltarune art: Random* assortment of characters
I drew this back in like february lol. Drew it for me and some of my irl friends to use as our pfps in discord. It was our fav characters at the time (and most likely still are)
Never posted this one on my insta tho lol. whoops!
There is a hidden NPC in the third to last room before the arcade machine in Cyber Field. They have different dialogue for both before and after you enter Queen's Mansion for the first time.