Can I accept an offer from a MS program, but continue applying to other schools?
Actually, to behave in a completely ethical manner, if you don't intent to honor your acceptance, then you should withdraw. But that is based on the basic idea that failure to do so could deny an opportunity to someone else. And, in light of the other things you say, I'll have to guess that the probability of that in this case is small. 

In some programs, it would be very important that you withdraw. For example if you have been accepted into a program with limited slots that are difficult to fill and that require expensive resources - medical programs, say. But that isn't the case here. 

In fact, the program that accepted you has probably accepted a few more people than they need to (course based masters) expecting that a few won't show up. It is fairly typical and is normally a good thing for them to do. 

I think that in the narrow case that you describe you can probably go on for a while leaving it as it is. Any transgression would be small. But you should inform them when you know that you won't honor the offer. 

I think the only consequences would be to your conscience.