Bozorg Agha was supposed to be in the flashbacks in seasons 2 and 3, but Ali Nasirian did not accept.
Taraneh Alidoosti (Shahrzad) and Shahab Hosseini (Ghobad) appeared in "About Ellie" and " Salesman" both directed by Asghar Farhadi.
There was no originally a third season, and episodes of season three actually belonged to season two, but the agents eventually turned it into a third season.
The series was supposed to have only one season, but the next seasons were made to the audience.