Corrected entry: The crystal set in the kid's trumpet is never discovered or spoken about. Though it isn't set off by the boy's playing it during the State of the Union address, it remains in the trumpet and we are left to believe that the boy who likes to play his trumpet at both school and home will set off the crystal and blow himself - and likely a large number of others - up.
Corrected entry: While the youth orchestra is playing the national anthem at the President's speech, the are several shots of a security camera showing Sam and the music notes being played. It looks like ARIIA is observing the scene, waiting for the note which is supposed to cause the explosion. How is that possible since Agent Perez has destroyed ARIIA several scenes before? (01:40:55 - 01:42:30)
Correction: ARIIA wasn't waiting for that note - there was a sonic triggering device planted in Sam Holloman's instrument under ARIIA's order, which was to detonate the hexamethylene bomb-necklace when that note was played.
That's not what they asked. They asked how ARIIA is watching considering Perez just seemingly destroyed ARIIA by shoving the metal rod in her 'eye'. And they did acknowledge that Sam had the detonator, but ARIIA was waiting for the note to be played at the end, for it to set off the Hex necklace. But their question is about HOW she was watching if she was supposedly destroyed.
Corrected entry: The Bomb (crystal-necklace) in the last scene would be triggered by frequency-response as soon as the trumpet hits the high F in the star spangled banner. The exact same 'high-F-note' has however by that time already been played by the trumpet (you can actually hear it) a few phrases earlier. Check any score of the anthem. The F sounds earlier on the word 'glare' (rockets red glare). So the bomb should already have been triggered.
Correction: The crystal was set in Rachel's necklace. The detonator was set in Sam's trumpet. The bomb would only detonate if Sam played it while in the same room with the crystal, which is exactly what happened.
Brad ★
Doesn't really answer their question. Rachel still - probably - has the necklace, and the kid still has the trumpet. So unless Jerry figures it out and tells her to get rid of the necklace, it can still detonate I mean he will probably play at home - where the necklace is.