After Papa Smurf leaves the village to help an enchanted prince, Greedy calls the other Smurfs to eat some soup that he has put some medicine in, one scene shows Papa Smurf helping the other Smurfs work on the dam, even though he's not in the village.
During "The Blue Plague" segment, Brainy Smurf goes to Gargamel's for help when the Smurfs start acting like birds. When Gargamel invites Brainy in, he closes the door. When Brainy reacts to Gargamel's request to go to the Smurf village, the door is opened. Then in the next shot, Gargamel opens the door to let Brainy out.