Stitch falls in love with a female experiment that looks like him and names her "Angel", but Lilo is both jealous and suspicious of her. When she later looks up Angel on Jumba's computer, she discovers that the experiment turns good experiments back to evil by singing her siren song and is working for Gantu. Stitch runs after Angel and finds out the truth too late. Now, it's up to Lilo, Jumba and Pleakley to save Stitch before the other experiments turn on their own cousin.
- Moral: You've got to believe in love.
- This episode is similar to an episode in Samurai Jack, in which three Sirens use their singing to brainwash Jack and many other people to do their bidding, and only the Scotsman (who is unaffected by their songs) breaks the spell by playing bagpipes.
- For obvious reasons, Angel is the only experiment to not be regarded as one of Stitch's relatives.
- Angel is a parody of Lorelei the Siren, as her song is an evil in the guise of beauty, much like the Sirens of ancient myth.
- In the Finnish version of the series, her name is Seireeni, meaning "Siren," and in the Arabic version, her name is Farasha, meaning "Butterfly."
- Angel is a likely reference to the Elvis Presley song "(You're the) Devil in Disguise", as she is considered by Stitch to be beautiful while she is (or was) evil on the inside.
- Like Stitch, Reuben has a similar crush on Angel, yet she neither shares the same feelings nor even likes him.
- Hämsterviel's phone number is revealed on Angel's pet tag, which she only wore in one scene: when she was running up Mount Waiʻaleʻale with Stitch following her. She never wore said tag any other time.
- After Angel turns the evil experiments back to good and Stitch commands them to get Gantu, Reuben breaks the fourth wall by saying, "Uh-oh, plot twist!"
- When Stitch gets blasted into a net, his feet are exposed, even though he should have easily fit inside the net.
- The net would have likely captured both Angel and Stitch in it.
- Due to a continuity error, the fur pattern on Angel's back is inconsistent in the series. In her debut, it is an upside-down heart. In "Snafu", it somewhat resembles Stitch's, and she also gains a marking on the back of her head, but these markings disappear in some scenes. In Leroy & Stitch, she does not have any markings on her back or the back of her head at all. The anime was also inconsistent with the patterns, with her having either the original upside-down heart back marking or the "Snafu" markings depending on the episode. Later merchandise did correct her back to having the upside-down heart-shaped marking.
- In addition, her fur was a deeper shade of pink in this episode, compared to all her later appearances.
- In spring 2004, Disney Channel held an online poll that asked viewers for their favorite experiments and episodes from Season 1 of the series. According to the top 10 results of that poll, "Angel" was the #1 most popular episode and experiment, likely foreshadowing the character's breakout status within the Lilo & Stitch franchise.