Treats: single cups of applesauce, mini gatorades or juice boxes. Nutri grain bars, single serve chips and cereals, lance crackers (beware peanut allergy), homemade muffins or cupcakes. dollar store toys, halloween pencils and cups (walgreens normally has them 8/$1. stickers, go to the birthday party favor section and check there. They sometimes have packs of four little decks of cards, kaleidoscopes, that kinda stuff.
Tricks: say abc's or ocunt to 10 while sticking tongue out.
maybe one of those soft indoor basketball hoops that hang on a wall or door. The "darts"game that uses velcro balls instead of darts,
Let them decorate a cupcake (provide sprinkles, icing, etc)
Good luck and have fun! If I don't get to post Happy birthday!