I feel like we’ve let ourselves forget how utterly bizarre Mothra and Gigan’s mutually assured destruction in Godzilla: Final Wars was. I think what happens is that Mothra’s scales cause the discs to malfunction and return to sender at murderous speeds… but that ability was only demonstrated once, in a different continuity.
As for how Mothra flies home during the end credits despite bursting into flames and exploding… yeah, I’ve got nothing. But it’s nice that she was able to dole out some payback after bursting into flames and exploding in her previous two Millennium appearances.
