Kara's pet cat Streaky was first mentioned in "Legion of Super-Heroes (2018)". In the comics, Streaky was a ginger cat from Earth who gained intelligence and Kryptonian superpowers from a rare isotope of Kryptonite. Here, he was a stray black cat Kara found near the Danvers' home shortly after arriving on Earth, but was never endowed with superpowers.
In the film Superman 2, Ursa says, " Did you see that? Did you see what I did? I have powers beyond reason here," after she kills a snake with her heat vision. When Selena uses her heat vision she says, " We have powers beyond reason here,"
When Supergirl arrives back at the DEO, Selena says "she actually cares for these humans, " just like General Zod says in Superman II.
The force field belt Winn creates is reminiscent of the force field belt Brainiac 5 of the Legion of Superheroes wore in the original DC comics.
When Selena and the others arrive on Earth, it is similar to the scene in Superman II (1980) featuring General Zod, Ursa and Non's arrival on Earth.