I'm not sure about plastic bags or any stuff like that, since I think realism is not exactly the goal of this game. But there is indeed a huge potential in this game. It could be interesting to add some bonus, some kind of temporary boosts that would activate randomly during a game, or if a certain amound of toys are collected in a realy short period. This bonus could be randomly chosen by the system. Here are some suggestion :
-additionnal time (teen or twenty seconds), extra points, enhanced speed, temporary toy grabber allowing you to attract toys from a short distance by pressing a key, or simply making the default grabing distance longer for a short while, temporary elve killer (or stunner), etc.
Randomly, some neutral bonus could also be generated by this system, bonus that would have no effect on the game itself, giving no advantage or disadvantage and therefor, would be as fun as frustrating. examples : temporary change of the footsteps noise (squicky sounds, splaching sounds or whatever), a random noise completely useless but fun, just popping as an empty bonus opportunity )could be a sound chosen amound a large repertory of toy sounds to make it funier), etc.
No need to say that this could be an opportunity to put some random achievement here.
Hoping you'll like those suggestions,
have a nice day!