To Jesus' immediate left are Thomas, James the Major, and Philip. Thomas and James are both upset; Philip appears to want an explanation. On the far right of the painting is the final group of three: Matthew, Jude Thaddeus, and Simon the Zealot. They are engaged in conversation amongst themselves, as if Matthew and Jude are hoping to get some sort of explanation from Simon.
As our eyes move across the painting, shifting from one apostle's reaction to the next, one thing which may become evident is how human the depiction of each figure is. There are no halos or any other marker of holiness - not even any symbols of divinity around Jesus himself. Every person is a human being, reacting in a human way. It is thus the human aspect of the moment which Leonardo Da Vinci was trying to capture and express, not the sacred or divine aspects usually focused on in Christian liturgy.