What have I done?

[JD]

I was under the car removing the brackets that brace the inlet manifold against the block. I had a socket on the bolt that attaches the right of the two brackets to the manifold, and putting force on it until it suddenly moved and the bolt loosened. Fine, got the bolt out with little trouble or so I thought. Just then I hear a sudden noise of water trickling down like coolant that was somewhere up top somehow draining back down somehow. the system isn't closed or fully topped up as the coolant hose to the TB up top is disconnected. It didn't feel like I hit anything and I can't see anything leaking anywhere. What just happened?

The car is on axle stands at the rear only so is tilted slightly. Have I done something stupid?

[IMR2T]

If there was no coolant/fluid visibly dripping and there's nothing stopping it from starting when you refil coolant etc then I wouldn't worry. You've perhaps dislodged some coolant or oil from a channel in the engine.