Obviously he did the whole hologram switch to turn off the planet, but he was asking for the antidote when the helicopter was crashing and couldn't have received it due to him being off somewhere concocting the ruse. Plot hole or was that his plan?
shareThis was his plan.
There's a point just after he's met with Carjack where he overhears (if I remember correctly, during a moment where the drug is giving him a bad headache or something) that the drug is absolute B.S, government propoganda.
It's at this point that we can assume that he's put the pieces together and starts to formulate his own plan and work on his own agenda.
Rest in Peaceful Oblivion, Christopher Hitchens. April 13, 1949 - December 15, 2011
Yes, Carjack clues him to the fact that it's "gov't propoganda. Just one more lie."
But I think what REALLY convinces him is when Map to the Stars Eddie says the he used to represent the guy that invented it. Eddie is a known liar at this point and Snake trusts no one. When he says it, Snake give him a "gimme an effing break" look and Eddie even has to swear (that he's telling the truth).
Immediately after, SNake says that he will take them all out on a helicopter and Eddie asks if it's true. Snake looks back and says "Swear to God, Eddie" lying right back to him. He now knows the Plutoxin 7 virus is a fugazi!
https://www.facebook.com/pages/Unofficial-Ash-vs-Evil-Dead/466308540194451