While in post, we decided to go with a shot where SPAG was not holding the knife
with the blade attached so we had to add it in using Photoshop and After Effects.

Before

After
Click on the images above to see the before and after footage.
 
We made a decision in preproduction that we would not use a real bird in the classroom due to the chaos that would bring. We attempted to shoot a real bird flying against a green screen, but that gave us less than adequate results. Then Ian Lang came to the rescue delivering a realistic computer generated bird.