You can watch this on Hidive, but it's also on YouTube:
Just before the floor collapses, they are scooped up by an Army helicopter.
The military recover the M-66 and disable it.
In a fit of niceness, the commanding officer lets Sybel go rather than disappearing her.
The incident is covered up as a terrorist bombing.
That's pretty much it.
So, what's my takeaway?
Well, this is an OVA from the 1980s, and is exactly what you'd expect from that.
There's nothing here that you need to see, but there's some nice fight choreography and some nice monster chase scenes.