In concept, this is fairly simple. Lift the tag and light strikes a photocell--triggering the action. The sound module plays a prerecorded "Eeek" and the package backs up, turns and takes off. The Arduino/Motor Shield monitors current going to the motors. When the package strikes an object, one or both motors struggle to operate and draw an increased amount of current. The increase in current lets the Arduino know it is time to play the "Eeek," then back up, turn and take off. This continues until the master toggle switch is turned off.
Add "+" from the recording module to the top of the relay/1n4004 diode.