Kid in Wolf Man Mask
This kid was captured by a snare trap set up by Dan, who mistook him for the Wolf man, due to his mask. He was presumably trying to trick or treat at Casa Paradiso. Chris arrives soon after, convincing Dan the kid was not the real wolf man, and scolded the kid for trick or treating alone. He was then let go, and ran off (not before kicking Chris) never to be seen again.
Kid in Yeti Mask
This was a child attempting to trick or treat at Dan's neighbors house. Immediately after letting the first kid go, Dan sees this child and once again mistakes him for the wolf man (though Chris points out he was wearing a yeti mask) and chases him down.
The child then ran down the street, screaming for help, and removing his mask (which Dan mistook as him reverting to human form). He continued screaming, which finally got the attention of a police officer.
It's unknown what exactly happened to him, as the scene cuts away.
A group of other Trick or Treaters. A girl dressed as Snow White, a girl dressed as Zorro, and a boy dressed as Dracula (specifically the Bela Lugosi version).
Nothing else is known about them.