lionhead

Question: Okay, so here is something that always bothered me, although I really like the Elves at Helm's Deep: how in Arda did they get there so quickly? Elrond and Galadriel decide to send the Elven army to the Hornburg during the telepathic conversation-scene, in which there's also footage of the Uruk-hai marching towards Helm's Deep, because, indeed, they have already departed. The Elves that Elrond and Galadriel send are from Lothlórien, they are Galadhrim, and they arrive at Helm's Deep quite some time before the Uruks do, despite a) Lothlórien being significantly further away from Helm's Deep than Isengard, and b) leaving after the Isengard army did. Just, how? I am not buying some random Galadhrim army just happened to be nearby, as it doesn't make any sense for them to be, especially considering the fact that Sauron was attacking Lórien at the time, so you'd think they'd be needed there. I am also not buying Galadriel teleported them or something, because if she could do that, she could have just teleported Frodo to Mount Doom. I know this is probably just something the film makers didn't think through, but can someone think of a plausible excuse?