Someone may have stated this already but I noticed how when Obito was running towards Kakashi and Rin he grabbed
his left eye( The eye Kakashi has).
When I saw that it made me think that Obito was possibly seeing what was going on through Kakashi since he was getting closer to him and because Kakashi opened up his Sharingan. This is NOT genjutsu.
Notice Kakashi's right eye is shut too. But basically their vision was linked for a moment.