What happened to the punishment for stealing an S-Rank Quest? 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?
Episode 19 (filler episode) and episode 20 (omake episode) are non-canonical from a continuity perspective. In the manga, when they return to Magnolia, Erza reminds them about that punishment (just like in the anime), but then they see their guild building destroyed. This begins the next Phantom Lord arc, and thus the punishment matter gets dropped naturally. Since the punishment was never shown in canon, they probably decided to skip it in the anime too. 


   In any case, that punishment is most likely something silly, such as the one in episode 75 later.