Everything indicates that he is not dreaming, except for the symbol, but if it's all a dream Quaid´s should never would have dreamt about Melina before he goes to RECALL and that entire first scene doesn´t make sense.
Now assuming that is all real there is no explanation for the symbol. So in my opinion it has the ending wrong.
There is no reference that the symbol is permanent. it could be as simple as an ink stamp and can be erased easily, so imho everything is real or as you say the first scene would make absolutely no sense.
