Ascended Fanon: The Brothers Chaps themselves forgot that the Fhqwhgads Robot's Fan Nickname "Visor Robot" was Fanon, and upon realizing their mistake, gave the nickname a why not instead of Jossing it.
Strong Sad was never sad that he was flying; that was a Powered By The Cheat version, not the real deal. His line "I don't like food anymore" was something Strong Bad dreamed up.
The Quote of the Week often supplies misquotes to some lines, such as Strong Sad himself saying "Some animal died!" or Senor Cardgage saying "You bet small girl! How 'bout I hit you on the slant?" This could be attributed to the creators using outtakes as quotes of the week.
Cash Cow Franchise: Not to the extent of other cash cows, but when co-creator Matt Chapman looked at all the T-shirt orders he received, he wondered "Are there even this many people in the world!?" The creators now live entirely off of the sales of their merchandise.
The Red Stapler: Strong Bad's BMW lighter. Though the Brothers Chaps had nothing to do with them eventually getting made, they weren't actually available when Strong Bad first started flashing one around, and continued to be so for years.
The creators have been guilty of this from time to time, mainly when the creators' family lives get in the way. Also, while Strong Bad Emails were originally meant to be released every week, they were later reduced to being "updated somedays" so that other kinds of cartoons could get their fair share.
From April to December 2010, the Brothers Chaps went over eight months without producing any new cartoons, a combination of family matters (both brothers are parents now) and working on other projects. The site began updating again in December before resuming the hiatus so that Matt Chapman could work in California on animation freelance work and Mike would take care of the families during this time. They finally updated again on April Fools' Day 2014, hanging a lampshade on the fact that the Brothers Chaps hadn't updated in years.
As of July 2014, Matt Chapman confirmed on the Jeff Rubin Show that he is back in Georgia and seriously wanting to bring back the series. The Brothers Chaps plan to rev the series back up sometime in Summer-Fall 2014.
All of the major characters except Marzipan, Pom Pom (who only speaks in bubbles), and The Poopsmith (who has only spoken once in the cartoon's entire history), are usually portrayed by one guy (Matt Chapman). And let's not get into the ramifications of the characters impersonating each other's voices...