Interestingly enough though, it wasn't entirely inaccurate. Towards the end of the war, German factories were turning out some frankenstein equipment.
Some K4's were given Mg 151/20's when the MK 108 was unavailable, some G10's were finished with the K4's 605DC engine instead of their own 605D.
I can't provide proof, but I've heard tell that at the very end of things, they were also taking near total loss airframes, and mothballed older models, and jamming them together with new engines to make bastard G-10's.