The droid known as AZ-34521 is the same droid that helped Echo's good friend Fives uncover a conspiracy about the clone inhibitor chips in season 6 of Star Wars: The Clone Wars (2008) series.
The title card that transitions from Star Wars: The Clone Wars (2008) to Star Wars: The Bad Batch (2021) was considered to be put after the waterfall scene, to help show exactly where this show steps out of that era. It was abandoned in favor of not interrupting the story.
The clone captain at the beginning of the episode is designated CC-10/994 but goes by the name Grey. In a graphic novel he was tasked with hunting down a young Caleb Dume and nearly succeeded until he finally came to his senses and sacrificed himself to let Caleb escape.
Depa Billaba and Caleb Dume's experiences during the execution of Order 66 were first explored in the 2015 Marvel Comics series "Kanan: The Last Padawan" written by Greg Weisman.
The episode was released on May the 4th, 2021 which is Star Wars Day.