hands across America?..

One of life's mysteries lol. Most of the movie doesn't make sense and/or straight up unfeasible anyways.

Agreed on what Grimace has said. To elaborate, I think her motive for doing it is yes, a childhood memory, she's sad she missed out, was a huge cool thing back then, so she wanted to recreate so she could participate. Beyond that, what a bold and creepy way to announce on a large scale "We're here!" Would definitely intimidate. As for the other Tethered. She had decades to orchestrate this, and it was probably easy to get them to obey. She probably dumbed down her communication, and they as long as she treats them well, they probably don't care about the why, only the what and the how. As for the how, we don't know how many portals they have scattered across the lands. As for the real Red, I think she kept her secret for the obvious reason that she's adapted and has a better life up here, that she had stolen and intended to keep.