I wanted to check my coolant level in the radiator, but when I pulled the cap off it came apart and the bottom part of the cap fell inside of the radiator. Will that do any damage and how could I get that at? I will attach a picture to show with fell inside.

I've already ordered a new cap from Acura

 

Hopefully the cap piece is lodged into the corner of the radiator and won't move internally. Worst case it causes overheating issues or issues with the coolant system if the piece somehow moves and flows through the hoses into the engine's water jacket/waterpump. Next time twist completely and then lift straight up, tilting it can rip the rubber off.

 

I suspect your are ok. The piece appears to be larger than a cooling tube so it won't travel trough a tube to the hose and pump.

 

Thanks for the valuable info csmeance. Ever since it happened it has been driving me crazy, thinking that I could have messed up big time. Well, I won't drive it anymore my anxiety is through the roof.

 

Thank you for your input, I really appreciate it.