Factual error: In the movie's opening scene, it's night and we see the full moon. There's an elderly priest lying in bed. The next morning we learn the priest has suffered a stroke and been taken to the hospital. That day, Prof. Birack pauses before entering a campus building to look toward the sun. We see a thin crescent moon near the sun, as if there will be an eclipse in the next few days. That night, Brian is waiting outside a campus building for Catherine to come out. He looks up at the full moon. In following days, other characters see the daytime crescent moon, still approaching the sun. It's impossible to see the full moon at night AND a crescent moon during the day in that brief a time span. It would be more like 12-14 days for the lunar phase cycle to progress from one to the other (much less back again).