Willy McBean and His Magic Machine (1965)

Frustrated genius Rasputin Von Rotten has decided to make his mark upon history once and for all by building a time machine to travel back to all the important achievements in history and take credit for them himself. The plan looks foolproof until his talking pet monkey Pablo runs off with the blueprints for the doctor's scheme. Pablo is discovered by boy genius Willy McBean, who decides to go back in time himself and undo the doctor's damage, if for no other reason than to keep from having to study history all over again.