sounds like he heard but didn't comply. If he's not listening, I advise you to got to him, get down on his level so that you can look him in the eye and state your request. Then, in the case of picking up toys, begin to pick them up with him by handing him a toy. If the TV is on or there is any other distraction turn it off. Usually,if there is nothing to distract a 4 yo and they have heard you they will do as asked.
I wouldn't use a threat, even of Santa's elf, to get him to do something. He needs to do it because it's the right thing to do. Sending him to his room when he doesn't comply is good. Just do it soon, before you run out of patience.
No need to stress. Tell him to do it while being sure to capture his attention and making it easy for him to comply. If he doesn't do it, he goes to his room until he's ready to come out and do it. In my daughter's house he could come out for dinner but he'd go right back to his room if he doesn't agree while at the table to pick up the toys. This is done calmly and in a matter of fact tone of voice. Either he does it or he doesn't and spends the time in his room. No stress.
You cannot make kids do anything. You can only set it up so that they choose to do it. And listening is a learned skill. We have to teach them to not only listen but to also hear what we say. That often means interrupting them when they're busy and getting down on their level and in their face so that they can see us.
My daughter has been doing this since her youngest was around 4 (he's now 7) and it's now rare that he spends any more than 5-15 minutes before coming out to apologize and do what he was told. Sometimes, all it takes is saying, "guess it's time to go to your room" and he immediately apologizes and does what he's been asked to to.
Tell your son ahead of time that this is the new plan. Then be consistent in enforcing it. He'll learn. My grandchildren can do whatever they want in their room but yet they come out and apologize and do what they were asked to do in a very short time.