The palpable uncomfortable "atmosphere" in the alien-created subspace was well created and maintained with lurid colors and fisheye camera perspectives.
The boxer alien's original form with the weird saucer-shaped head and eyestalks appears to be a take on an Ultraman monster, Kanegon.
Kanegon is relatively well known for a Ultraman monster
Kanegon is associated with money (Okane == money in Japanese), which sometimes transforms humans into Kanegon form, which makes the Dan Da Dan-version's "salaryman" motif appropriate.
The upgraded boxer alien's form has a similar profile to the Baltan aliens from Ultraman,
And the Serpo aliens' white with black geometric stripes resembles the Dada aliens from Ultraman.
The Ultraman Dada aliens also kidnap human specimens for unknown research purposes, and are associated with the number 3, having 3 faces.
The Serpo aliens' profile resembles alien Pegassa once again from Ultraman
Episode 8 is relatively weak, but the loose threads there were resolved in Episode 9. The final gag is overdone in many shows, but somehow, the way it's executed here makes it feel fresh and made me laugh hard out of second-hand embarrassment.
As usual, it's absolute cinema. It's one of those things that make 30 minutes feel like 5.
The cinematography and art direction continues to impress me. Changes in field of view, angles, colors... just everything comes together so well. It makes even the silly dialog scenes stand out.
I also REALLY love this callback to the original Acrobatic Silky:
As for the joke at the end, we all saw it coming and yet they still made it funny with the fisheye field of view, wacky animation, and cartoony art style
It's about the song that the Serpo sings when he's transforming the boxer alien into the mantis shrimp/Baltan-like form.
The song named "Yuuki No Shirushi" or "Sign of Courage" was from a 80s commercial for Regain an energy drink, that became an anthem for the work-yourself-to-death zeitgeist in Japan at the time.
The comments under the video say that...
spoiler
...the manga later reveals that the Serpo injected the boxer alien with one of their energy drinks, so that song is appropriate.