The removed original heads of Abolas and Banila used in the show still remain in existence as they are often displayed at exhibitions (I have actually seen them).
According to the settings recently publicized, the birthplace of Abolas and Banila seems to be described as “Myū Empire” although I don’t know since when.
The preparatory script of this episode appears to have been written under the title “Emissary from Ancient Times (zenseiki karano shisha)” by Masahiro Yamada. And the final version of the script as “Demons Rise Again” was co-written by Yamada and Ryū Minamikawa, the pseudonym of Samaji Nonagase, the director of this episode.
In the preparatory script, chances are that the two capsules found out contained Abolas and an ancient human instead of Banila while Fuji assumed the mission of the ancient human could be to destroy the civilization if he should realize it is an evil one when he woke up from the long sleep in the capsule.
While the ancient human brought Abolas back to life at the stadium, it is likely that he was set to be shot dead by Arashi and that Abolas was to lose his life exposed to his own foam after fighting with Ultraman.
It seems that the concept of kaijus emerging from capsules served as the original idea of Capsule Kaijus of “Ultraseven.”
It is said, in the final script, the episode was to end with the scene of Abolas being smashed into pieces by Spacium Beam to be scattered around at Ultraman’s feet without showing Ultraman flying away.
It is also well known that the tokusatsu part of this episode was directed by Eiji Tsuburaya at least partly to help out the staff troubled by the delayed filming.