'plus' is not a verb - the word you want is 'add'. When does the word behind "any" need an "s" added?
Usually, you do need the 's' - because you want to know about all the mistakes, not just one. If you have the possibility of more than one (such as mistakes) - you should use the plural, and say 'are there any mistakes'.
If you only want to know about one option, then you should use the singular form. One example is if you want to know if an option exists. An example of this is 'Is there any way to get my parcel delivered today'.
So - the general idea is 'how many do you expect, or want to know about'?