Reply To: TVLine 3/2 – Ask Ausiello – Casting Two Brothers for Season Finale

From the same source who provided the Cleo Fox casting info:

http://desperationandgin.tumblr.com/post/140247687423/more-casting-calls

I think the episode numbers are a mistake and that they meant to say 522 and 523, not 521 and 522. TVLine said it was for the final 2 episodes of the Season, and the Prince Marcus call for 521 has different filming dates. 521 already started filming:

http://desperationandgin.tumblr.com/post/139935742388/a-little-more-casting-news-prince-marcus-late

So logically

521 – February 26th-March 9th
522 – March 9th-March 21st
523 – March 21st-April 2nd