This is an exothermic reaction, so stand back to avoid burns from the heat. The audience should be kept back to prevent them from getting any of the foam on them and to protect from the heat. Also, be careful of the solution in the bottom of the container/flask and the foam as there could be unreacted hydrogen peroxide present.
Hydrogen peroxide is a strong oxidizer and is a very corrosive solution. Wear gloves, goggles and a lab coat at all times. Keep audience members away from the solutions and use extreme caution when cleaning up. Also, do not inhale fumes or use in an enclosed area. This solution can cause serious burns or irritation if it comes into contact with the eyes or skin and can cause respiratory issues if inhaled.
For the full MSDS please visit this link: http://www.sciencelab.com/msds.php?msdsId=9924299