Remove plastic wrap from popcorn bag and unfold bag. Place in the microwave, directions-side up. Cook until bag is inflated and popcorn is popped, 1 1/2 to 2 1/2 minutes. Carefully open top of bag by pulling from the corners. Transfer popcorn to a bowl.
Melt chocolate chips with vegetable oil in top of a double boiler over simmering water, stirring frequently and scraping down the sides with a rubber spatula to avoid scorching, about 5 minutes.
Zest orange using a fine grater.
Juice 1/2 of the orange and stir into melted chocolate mixture; pour over popcorn and mix well. Stir orange zest into popcorn mixture.
Line a baking sheet with aluminum foil. Spread popcorn mixture on top in 1 layer. Allow chocolate to cool and dry, about 30 minutes. Break into smaller pieces.
Sift a generous amount of confectioners' sugar over popcorn.