Already in the movie, all the frogs have died,

as you clearly seen when it started raining

frogs on Ben's head.

Ben is sitting, dissecting a frog, and Katherine is

looking at pictures on her computer. The lights go and Katherine starts looking for Doug. As Katherine

walks into Doug's room, the wind blows the doors

to the balcony wide open reveling a record player

playing a skipping record. She takes the needle off the record and looks off the balcony and sees a

a shining light of some sort in the woods which is Ben standing at his ex wifes grave. As Katherine is

standing on the balcony, you clearly hear the sound

of chirping frogs in the background.

ALL the frogs in the town are supposed to be dead.

Not just the ones by the river, cause the frogs

didn't die of poisoning, yet of an act of God.