A note is delivered in a pizza box, with the written warning 'they're listening.' Guy proceeds to read it aloud.
The guy reading it aloud is narration from the character that delivered the pizza. Neither character in the scene is reading the note out loud, they're reading to themselves, the narration is delivered from off screen.
As they drive to meet him, the 'espionage' music has sonar sounds.
The tasers sound like guns with silencers.
The military facility appears to be a hydroelectric plant.