The cancer of the first victim is initially identified by the oncologist as a carcinoma, which is incorrect. It is later correctly identified as a melanoma by Dr. Bishop. No oncologist would make such a mistake.
The Massachusetts Drivers License shows the image on the right side. Massachusetts drivers licenses have the image on the left side.
Walter (John Noble) mentions that bleeding from the eyes could be caused by a mixture called Tears of Ra. Actually, in Egyptian mythology, honey bees were the tears of the sun god Ra (thus, "Tears of Ra"). In this context, the bee was seen as the messenger of the gods, falling down, like tears, towards the earth (and man) to pass on some secret message.
When Alternate Astrid blurts out "Deus ex Machina," Walter asks, "The hand of God?" This phrase actually translates into "God from a machine" a plot device in Ancient Greek drama that amounted to a last-minute rescue by an omnipotent force. Neither Walter's translation nor Alternate Astrid's use of the phrase are accurate. The correct Latin term for Hand of God is "Manus Dei."