Can the Japanese present tense indicate a continuous acton?

I was watching Shirobako episode 16. and at 2:31 the witch says "落ちる！" as she falls out of a plane. The subs translated it as "We're falling!" but I'm confused on why that is so. I'm not sure if present tense of a verb can be used to indicate continuous action. In this situation, why isn't it "We're going to fall!" instead of "We're falling!" or 落ちる最中 instead of 落ちる?