Perception of abrupt noise
Judging from your description I think it has to do with the predictability of a certain event (the activation of the toy in this case) after a certain action (the hand clapping), altering your perception of temporal order between the event and your action. David Eagleman has done some research on this suggesting that when one has the intention of generating a certain event that has a high probability to occur, this event can be perceived to happen earlier than the action that caused it. That maybe explains why it especially happens when you are the agent. At least that is what I got from reading this paper http://www.psych.usyd.edu.au/staff/alexh/research/papers/EaglemanHolcombeTiCS2002.pdf Feel free to correct me if you think my description is wrong.

Nevertheless, the field of time perception has generally revealed many illusions in human timing and if you are interested in more you can read the work of Benjamin Libet as well on time and conscious awareness http://www.amazon.com/Mind-Time-Consciousness-Perspectives-Neuroscience/dp/067401846X