No, I have never been able to put the lense on incorectly and have it stay attached to the camera body.

Line up the red dot on the lens, to the red dot on the body (down near the shutter release), insert lens and twist until it locks.

I just want to check something....

The shots with the lens at infinity are in focus? If so then your mirror or ground glass are out of place.

If the shots are in focus in the viewfinder, and on film then the lens is out of whack and should be easy to fix.