Visible crew/equipment: Right after Cerebro begins to kill all the mutants, Mystique gets down on her knees in pain and tells Magneto to hurry. The next scene is a shot of Stryker running down a corridor and opening a door to go outside. Before he opens the door, you can see the shadow of a crew member going across the door.
Visible crew/equipment: When Magneto and Xavier are speaking inside the plastic prison , look to the right of Xavier's head when Magneto says something about "failure with Stryker's son". There is a partial view of a piece of some kind of equipment moving around lightly reflected in the glass. It's definitely not one of the actors by it's shape.
Visible crew/equipment: When Nightcrawler and Storm teleport into Cerebro 2, a crew member with a white hat is visible beneath the bridge to the bottom right.
Visible crew/equipment: In the jet at the end, what looks like the reflector screen is reflected in Cyclops' visor. This happens in at least two scenes.
Answer: Presumably he is sensing the presence of Jean/Phoenix.
BaconIsMyBFF