When Brand tries to sabotage the launching Jeremy Wilkin can be heard saying He's got a gun! Look out!
What character is he? There's only Scarlet Brand, the Vice President at his wife there.

How come Brand's pass card has a picture of Captain Indigo from Spectrum Strikes Back? And how come Harmony doesn't notice?

Its the same puppet for both roles.

Yeah I know, just noting they used stock photo thingy, and if Harmony had any brains she'd say 'hey you're captain indigo and you're dead!'

Mervin Brand calls himself 'Marvin' when talking to the Angels.

In the biographical section over at the S.I.G. homepage, Harmony is described as taking over her father's aviation business after his death. This episode makes it plain that her father is alive and well and learning Judo from his daughter.

(And don't you just wish that Brand HAD taken a swing at Harmony? I can see him showing up at the launching with his arm in a sling....)

It sure took Captain Blue a long time to feel suspicious about the car that pulled up close to the President's house, and then just sat there.

Does anyone know exactly what Harmony said to Brand, immediately before she started telling him about her father?

This was one of those rare occasions where the Mysteron agent doesn't actually die right away. Considering that Captain Scarlet does not have to face an immobile radio transmitter, he could have made his report while keeping an eye on the downed Brand. (Would have saved the special effects crew from an expensive explosion!)