If you remember, according to the book Draco threw Peruvian Instant Darkness Powder into the air so no one could see, but he had his Hand of Glory (which allows the holder to see in any darkness)- so one could assume that Draco was leading Goyle and Blaise Zabini (that's who the black kid actually is) to the Room of Requirement. I can't remember for sure from the movie, but if the Apparated to that corridor they might have held hands to make sure they land in the same place...... or you could just go along thinking they are faggots....