...and you'll be hypnoti-i-ized.
I don't get why there was any doubt in Dipper's mind later in the episode that the song had a hypnotizing effect on Wendy, when it ended with this line. I also don't get why Dipper wasn't affected.
You'll understand when you're older.
Contrary to their maturity levels, Mabel is actually older than Dipper (albeit only by 5 minutes.) According to Alex Hirsch, she brings this up occasionally and uses the above excuse, much to Dipper's annoyance.
Stan stocking meat for the apocalypse...
What makes Stan think the apocalypse is coming? Also, what makes him think he can survive it?
Our favorite 50's-themed 1970's diner.
This New Age Tree Hugger starts playing this Transcendentalist Hippie music.
Dimensional Healing with Thistle Downe
This is what the sign said
For you specifically. Not the girl sittin' next to you, but you.
Music has subliminal mind control hidden in it all the time.
This is an obvious reference to the backwards message in the theme song, telling you how to decode the cryptograms in the credits.
Money! Money we stole! ... / Stan and Dipper's expressions...
Stan and Dipper had mortified expressions on their faces. I feel like they would've pushed the issue, if they didn't have their own mystery to solve.
goat eating the license plate / Good boy.
If the goat is Bill, this scene would make a lot more sense. Bill eats the license plate, causing a chain reaction that makes Mabel set the boys free. The boys, with their synthesized music, would be a threat to Bill if they ever joined Mabel in a fight against him. Soos sees Gompers eating Bratzman's license plate. Knowing that Bratzman could get pulled over and arrested for this, and not liking him due to their previous encounter, he says "Good boy."