Board Thread:Show-Related Questions and Answers/@comment-24867198-20160114043414/@comment-26159109-20160114054113

I can't believe this is still a question. Look, what happened in season 4 was a special case. They added the episode AFTER a few episodes were written, so they made alterations.

This season, the episode was announced BEFORE they wrote the script, that's why it has his "own" number 509. It doesn't affect any future episode, and even the season finale will have two different numbers like season 4 finale. This season will have 23 episodes, 23 hours, 23 production codes, 23 titles, 23 titlespoilers, 23 whatever...