There is a weird interaction here and I am not a ip lawyer and do not know how to resolve it But I will try to explain.
There is steamboat willie(the work) it is in public domain and you are able to distribute it and modified copied of it freely, the weird interaction is where and how it conflicts with mickey mouse which is still a registered trademark of disney. And items bearing that mark are protected as such.
So I think legally to distribute a variant of steamboat willie you would also have to prove how your use of mickey mouse does not infringe on disney's trademark. You have to show how your product can not be confused with a disney product. Put a big "Not a disney product" on the back?
There is steamboat willie(the work) it is in public domain and you are able to distribute it and modified copied of it freely, the weird interaction is where and how it conflicts with mickey mouse which is still a registered trademark of disney. And items bearing that mark are protected as such.
So I think legally to distribute a variant of steamboat willie you would also have to prove how your use of mickey mouse does not infringe on disney's trademark. You have to show how your product can not be confused with a disney product. Put a big "Not a disney product" on the back?