It does look like the film slipped off the take up spool.
Someone else mentioned we've all done it. I know I have. Those, by the way were the best ones I had ever taken.(HA!)

With a camera like this, I make sure the film is secure on the take up by advancing an extra frame, closing the back and putting tension on the film by turning the rewind knob in the direction of the arrow WITHOUT pushing the button on the bottom of the camera. Then, when you advance the camera, you should see the RW knob rotate.

You say these were the last two frames you took. Were you watching the counter or did the camera stop advancing? If it stopped advancing, it get to the end of the roll. If you were watching the counter, it works even if the film isn't connected or even if the camera is empty.