It's pretty easy to tell if they filled the engine with oil before sending it out. Are the hoses, engine cover, hood liner, etc. covered in oil? If not, they didn't fill the engine. There is no way for oil to spray out of the filler hole without touching anything in the engine bay, and once oil comes into contact with a surface, you're not getting it off without some solvents.
If there is still some oil in the engine, collect a sample and send it out for analysis. For $20-$50, that will give you a good idea of what kind of work is required without having to pay someone to take the engine apart. Based on wear metals and other contaminants, you should be able to determine what components have failed or have exceeded operational limits.