In the background of the first scene set in front of the school, several buses with Mireille and Aurore on the side can be seen. These are advertisements for the KIDZ+ weather girl competition from Stormy Weather (2015).
On the post-it that Marinette puts on Adrien's gift, it says "Bises", which is French for "Kisses", in the closure of a letter. It is the equivalent of the English word, "Love."