The shot of Greg smashing Tessa's potion basket was accomplished in one take, with several of the glass potion bottles flying off-camera and actually shattering against the camera operator, who continued rolling.
The TIMOTHY-1 satellite, as seen in the film, was built over the course of two weeks with dryer ducts, VCR innards, plywood, and plexiglass. It survived multiple takes of being smashed on the ground.
In the original script, it was one of Tessa's own potions that ignited the fuse on the satellite.
'James Franco''s agent was approached with an offer for the actor to read for the role of Greg, but academic scheduling conflicts prevented his involvement.
The name "Feathergrass" came about when the director happened upon a goose's feather blowing through the grass on the bank of the Charles River in Cambridge, MA. He later remarked that the name made sense for the character, given his outer-space aspirations versus his earth-bound reality.