This is the first time that Kara has no interaction with Alex.
At the beginning of the episode, Lena mentions the ability to infuse DNA into plants by coating the surface of metal particles and infiltrating the interior. This technology actually exists; it is called a gene gun.
The getaway car that the cult members use to kidnap Tanya has a license plate reading "590 WUG". Tanya's character is a linguistics professor, so this is likely a reference to wugs, small cartoonish birds used in a famous linguistics experiment on child language acquisition that are popularly used as a symbol for the field of linguistics.
This episode is the first time since season 2 that Mon-El wears his dorky human disguise of glasses and a sweater similar to the look of Kara and Clark when they are in a civilian setting.
The games arcade is called "Fun Centre" using the British English spelling (prevalent across the British commonwealth), a clue to the fact that it was filmed in Canada.