In the climax, the jungspars scream in agony when exposed to even a single flashlight. Light is their weakness. However, when Emily first encounters them and the police come (Flashing lights, headlights, with flashlights), they just disappear without a trace. No screaming, crouching or anything.
It's said that the Jungspars appear every 20 years, yet the old man was abducted 50 years ago. This is 10 years too early or late. Whilst it's possible the 20 years aren't an exact schedule, you'd think it would be mentioned.
Christopher vanishes standing near Emily without a sound or trace. It's implied multiple times that the Jungspars can't abduct people without their consent. Christopher, as scared as he might get sometimes, wouldn't say yes when Emily's with him.