It is possible to see Thor's hammer in a particular level on Black Ops 2. To do this, you need to be on the Celerium mission (level 2). Play through until you get to the point where you fly in using the special suits. Once you have landed and killed all the initial enemies, go to the cliff and drop down to a lower section. You should see a dark cave that you can go into. Light it up with gunfire or flash bangs to see the hammer.