Smoke grenades have a short fuse, and if you cook one you can easily notice now that they completely lose their horizontal velocity and simply plummet out of the air when they're triggered. Didn't notice this in the last version.
I haven't tried this yet with C4 or mines, but when you throw an IED from the prone position, it throws it further than if you were in any other stance.
It's not a simulation, it's a video game...
Smoke grenades seem to plummet right into the ground when they detonate while still in the air.