Rex is seen opening up Episode 20 of Fairy Tail so that he can write the script for the Narrator to... well narrate... and after writing the first bit... he comes to the episode's title.

Rex: "Wait is this another Filer Episode! Cause I swear to go-"

[Natsu & The Dragon Egg]

Rex: "Oh! It's the flashback episode... well I can just skip thi- Wait... last chapter was already a Flashback Episode... and I didn't even...
I CAN SEE INTO THE FUTURE!"

The boy yelled happily as he threw his hands into the air with a smile on his face!

Rex: "THANK YOU TIRED 3:00AM REX FOR THINKING OF AND WRITING SAD BACKSTORY! HAHA! ONTO THE PHANTOM LORD ARC BABY!"