This episode moved super fast for me and will likely rewatch but I somehow missed the jump from the replacement snake making it back to snake world to the invasion. The snakes realize there's more to the universe than their own world and try to take over?
Also, Jerry's call to Beth going straight to voicemail because she doesn't have his number on her phone...oof.
Think about what humanity may do if an unidentified flying object came and left another human who was similar but different than us who was kept in captivity with another species? It's shown a bit in the episode the Earth snake speaks a different language than them, but they decode it and communicate with it. And that snake probably has some tales being kept in a pet store, brought by a child human into a space suit, sent through space and ejected to that planet.
They make some social commentary jokes about how this is in the Snake Year 2256 or so, and the world has become so divided and hateful that they're going to destroy themselves, they've reached their peak and won't progress because they want bloodshed, power and destruction. But with this discovery they have a new force to unify and focus their hate towards (though other snakes want to protect them so there's a further civil war going on hinted as well).
Also it's a Terminator/Time Travel story parody, because as we find out the "modern" snakes didn't invent a time machine, they just started to. but because the snakes were en route to build a time machine they could start time travelling back in time already because it was made, and this lead to soldiers from the future going back to the past to cause bullshit... And then the rest of the episode goes on to mock time travel p lots because they become too convoluted and messy.
Yeah pretty much.
The snakes were supposed to destroy themselves in a snake-based race war because Morty killed their snake space envoy. By replacing it with an earth snake, who they figure out how to communicate with, they learn that there are other threats in the universe and up their technology, starting development on snake time travel AND snake skynet.
So in like 2026, the snakes finish time travel and snake skynet gets activated and destroys the world, but the children of the snake that Morty sent form the snake resistance, so snake skynet sends snake terminators back in time to present day terminate Morty, hence Snake Kyle Reese being sent to protect him. Then the snakes send even MORE snake terminators who get stopped by the snake terminator covered in human skin that the snake resistance sent.
Rick realizes that the only way to stop this is to destroy the snake society with time travel before Morty got involved, so they travel to the snake pentagon (currently under siege by snake terminators sent to kill the snake that Morty sent because killing Morty didn't work out) and invent snake time travel, then throw it back into the snake 80s so it gets invented before Morty gets involved. As a result, snakes go back in time to kill snake hitler, but nazi snakes go back to stop them, along with snake terminators who go back to make sure that killing snake hitler doesn't change the timeline for snake skynet, and it creates a never-ending loop of snakes going back stop other snakes from either changing the timeline or keeping it the same.
And Jerry originally dies because he can't hang onto the plane, so at some point in one of the snake futures, the snakes send the most advanced snake we see back to save Jerry, and it inadvertently does by crashing the plane. We don't know WHY saving Jerry was important.
We're seeing ALL of that happen simultaneously. We're seeing the plot of Terminator 1 happen like it did in Terminator Genisys without the context of ANY of the other films. Imagine if in the first Terminator there was an old man Arnold already waiting for young Arnold and Sarah Connor was already a badass and a T-1000 arrives to kill Kyle Reese and John Connor is a robot, but you didn't know what any of that shit was because it was the first terminator but we're seeing it in real time. The effect of every subsequent Terminator film affecting the first happening in real time