Originally, the plot for the game was to have the player portray a role of a undercover cop infiltrating the Saints, but this idea was scrapped as the developers felt it wasn't like Saints Row.
THQ had announced plans for a big massive expansion pack for Saints Row: The Third titled "Enter the Dominatrix" which was planned to be released in late 2012. However due to time constraints and THQ's bankruptcy, it was later merged with Saints Row IV and made a full sequel.
After every main mission you do, it will be on the news radio station explaining what happened.
During the mission "Party Time" the syndicate leader gives the boss the code to the elevator which is "3131", this same exact code was used in the first Saints Row during the mission "All The King's Men" where the Protagonist, Johnny Gat, and Benjamin King go and take out Tanya after she gained controlled of the Vice Kings.
"The film "A Haunted House" has a release poster in the background after the family begins moving into their new household.