In episode 19, Natsu, Gray, Happy and Lucie should have been punished because they "stole" an S-Rank quest. However, the master wasn't there, so they wanted to take another quest. When they read the quest content, it swapped their bodies/minds. The master then entered and tried to help them, and the episode ends.
Episode 20 starts in a forest where Natsu and Happy are fishing, so the "ending" of Episode 19 is missing.
Did I watch a wrong "source" or is this part really missing?