I'd refer you back to the video tutorials I linked to above, where a version of a 'dream machine' assistance device is used. There is definitely a tendency to want to arch and throw the legs back, such that Dave cues you to think of and look to the toes directing the movement, and scooping forward. This helps prevent that flailing of the lower extremities as you roll back to support.
I am in no position to advise on these types of moves, they are still 'advanced' from my dim perspective/experience. More knowledgeable persons on this forum will usually suggest you are not properly prepared for the movement, and refer you back to more basic material. I would recommend getting a mat, though, as a sensible safety precaution, you will probably be injured if you fall on that hard surface.