Pre-release theories
Dru will not appear in the film because he returned to the mansion he lived in the third film.
- Or alternatively, he will appear on the film, either working for the villains or already having been arrested by the AVL.
Poppy’s backstory.
Poppy was part of the orphanage Margo, Edith and Agnes were adopted from by Gru in the first movie, who became an aspiring supervillain after never being adopted. Poppy will be revealed to be Maxime and Valentina’s daughter who got sent to the orphanage for unknown reasons. The Japanese Title
The Japanese title of this movie is "Minion Super Transformation". This could imply the movie will feature the Minions getting their own transformer style mech (since a Minion turning into a giant had already been done before) to fight off the Big Bad, possibly as the movie's climax.