The last kaiju (monster) film Tomoyuki Tanaka would work on. This film was released a few months after his death. Tanaka created Godzilla and produced every Toho Co. Ltd. tokusatsu (special effects) movie between Godzilla (1954) and this.
Dagahra is the only villain in the Rebirth of Mothra trilogy to not be a Ghidorah.
The theme that played when Aqua Mothra dived into the ocean is reused for the final battle between Armor Mothra and Grand King Ghidorah in Rebirth of Mothra 3.
One of the concept art for Dagahra resembles Bagan's head.
Bagan is a monster that supposedly appeared in numerous Heisei Era Godzilla films including Godzilla vs. Bagan and Mothra vs. Bagan, but was scrapped during production.