Jimmy creates a machine that zaps his intelligence away in order to fit in, while his missing brains are needed to stop a meteor aimed at Retroville./ Jimmy builds a candy selling robot salesman who won't take no for an answer.
Jimmy turns his babysitting Grandma into a toddler to avoid her elderly rants and rambles/ Jimmy goes back in time to convince his dad to invest in a successful fast food chain, making the family rich in the present.
Jimmy and his friends use a sub to find treasure hidden in an old, sunken ship somewhere on the ocean floor/Carl confronts his nightmares of the "terrible spooky thing" by allowing Jimmy to enter his dreams.
Jimmy attacks the earth's atmosphere with sun block to end Retroville's heatwave causing a second ice age instead. / Jimmy creates musical instruments that play based on thought waves to beat Cindy and Libby in a school talent show.
After consistently finishing last in his gym class races, Jimmy invents a pair of super fast running shoes until things get out of control/ Jimmy's new experiment goes horribly wrong causing him to switch bodies with Cindy.
A dare leads Jimmy and pals to stay over night at Retroland to prove once and fall all the existence of the park's phantom/ Not to dissimilar to 1958's 'The Fly', an accident rearranges the bodies and heads of Jimmy and Carl's pet hamster.