It seems unlikely you would've been been able to check your knowledge due to the nature of the grading system being employed.
In my experience, getting a final exam back complete with annotations and corrections is generally not done: you simply get a grade reported. In the case of you being the only one taking the exam (e.g., the professor let you take it after everyone decided not to show up), you would've gotten an automatic 100.
That is to say, you could very well not know anything correctly, not realize it, and be none the wiser when you get your grade back.
In my experience, getting a final exam back complete with annotations and corrections is generally not done: you simply get a grade reported. In the case of you being the only one taking the exam (e.g., the professor let you take it after everyone decided not to show up), you would've gotten an automatic 100.
That is to say, you could very well not know anything correctly, not realize it, and be none the wiser when you get your grade back.