Packie and Gerry are the only siblings that do not wear their trademark clothes on the cover for this season.
Season 3 has a unique cover, which has the names of every comic up to "Dodgeball Mishap" behind the five siblings. The three prequels were also included, though at the time the cover was created, none of them were released yet.
Also, the cover for Season 3 appears to foreshadow how the series will go to have five seasons only, as that is what it ends at, though there is plenty of space to make a gag about a possible Season 6 but nothing is there.
However, a sixth season has been announced and will debut in 2018, thus meaning Season 5 is not the end.
This is the longest season in terms of how long it took for all comics to be completed, due to the two hiatuses that took place; one from September 2014 to January 2015, and from January to July 2015.
Oddly, the first and last comics of the season both have parantheses in their comic titles, and are the only two comics in the series thus far to do so.