A BBC documentary film crew has been held at gunpoint for over three hours while trying to sneak into the world’s most famous secret base – Area 51, otherwise known as Groom Lake / Dreamland. The Groom Lake facility has no perimeter fence to keep out intruders, but instead uses a network of hidden sensors and cameras that can detect when anyone crosses onto the base. Private security guards also patrol in unmarked jeeps.   Documentary maker Darren Perks and his film crew were arrested at gunpoint while filming ”UFO: Conspiracy Road Trip’ documentary, which airs next Monday; the footage will show the incident where they are arrested at gunpoint.   They were forced to lie on the ground for three hours as guards…