This episode was originally the final episode of season one, it was then decided to move it to season two as the opener. You can clearly see that hairstyles (especially Gar and Koriand'r) are the same as in the season one episodes, from the next episode two they all change.
First in-series appearance of Bruce Wayne in a speaking role.
First series appearance of Donna Troy/Wonder Girl in her iconic red star-spangled costume.