Terminator Genisys: 18 Stupidest Moments In 2015's Dumbest Movie
15. Acid Only Works When It's Favourable To The Plot
On two separate occasions in the film, Arnie's Old Man Terminator (let's all vow not to refer to him as Pops, eh?) improvises to use Actual Science to take down super killer assassin bots.
Right after Kyle Reese jumps back to the new 1984 and scraps with the strangely inconsistently powered T-1000, Sarah Connor shoots the ceiling where there are lots of tanks of acid to melt the Terminator. It inevitably fails to work entirely and T-1000 manages a Fatal Attraction style resurrection despite being mostly melted, at which point the T-800 grabs it by the neck and holds it under the acid downpour.
It melts, grotesquely and wonderfully, and so does the flesh on the T-800's arm. Naturally, it's acid. But the metal skeleton seems impervious, and able to be protected with a few squirts of (presumably) something alkaline. Except that makes no bloody sense, because almost the next scene shows the same model of Terminator being literally melted in an acid bath.