hi, I don't know too much or anything about cars, but I have a 07 mazda 3 an about 4 months ago I had a whole transmission overhaul done. Well everything has been running fine since then, but just yesterday I was driving home an went over a cattle guard. I wasn't speeding maybe going about 30 mph. After I went over it, the engine startd making a loud motor sounding noise like a generator. I kept going an made it home as I was only about 2 miles frm home. The next morning I tried to turn it on an reverse, an the car made a loud cranking noise then moved about 2 feet in reverse then started making a loud grinding so I put it back in park, n while I wz in park position, it started rolling back. After that it would not go into any gear at all so I shut it off. Then tried to restart an it would not even start anymore. We looked under the hood an here the whole engine had dropped down an was leaning towards the passenger side. There was also a cple drops of oil on the ground, an you could see the tranny an engine hanging under the car. How could this happen, or what happened? Anyone have any clue. I'd really appreciate the help!

 

Well since the passenger side has only one engine mount, i'd assume they didn't tighten the engine side properly when the replaced the transmission. The bolts probably loostened up and fell out / broke off.
Open the hood, there should be an obvious issue on the passenger side - i'd definitely say it's the shops fault if the engine mount disconnected from the engine.