The lower part of the shattered-reality stuff left by the dream bubble’s destruction forms a stylized skull. It’s easiest to see reflected in Dave’s shades:
And I think the Terminator face on the Cairo Sarcophagus is supposed to resemble (a dead) Jake:
Look at the two front-and-center teeth. Those aren’t the Terminator’s teeth; they look more like the buck teeth of Jake English. The black area around the glowing eye-lights also suggests glasses to me, especially since we just saw red lights glowing against black on another pair of glasses. That’s more of a reach, though.
Caliborn complained that was Jake “jacking his swagger” by wearing a helmet resembling his face; returning the “favor” by wearing Jake’s likeness seems like something Caliborn might do. So does twisting it into a death mask.
