When you first find the geishas on the mission Reiko sends you on, you'll see some lockers near them. If you open up the one with a darker door than the others and look on the inside, you'll see some photos of the developers wearing blonde wigs.

In the Gaming District level, as part of “The game II” mission, you will be forced to climb a slope with exploding bunnies raining down on you. On the left side of the slope is an escalator that’s moving downward and wont let you walk up. However, if you face the escalator and push the joy stick all the way forward then press the jump button with perfect timing (as soon as your feet touch the ground, jump up again), you can slowly hop up the escalator, thus bypassing the deadly bunnies.