To be honest, having finished it on the weekend, I don't recall there being any errors. I don't recall many of the answers off hand, but looking at the clue for 19A, I recall that it was right and did indeed equate to 2D minus a square number
Didn't trust my maths so kept my workings & answers on scrap paper. Have therefore been able to check and see no problem with the clue / answers - 19A is definitely equal to 2D minus a square