There's the ordinary engine and gear check, but occasionally you should also check your aircraft for hidden hairy passengers. Two folks flying an open-cockpit sailplane in Kourou, French Guiana realised that mid-flight when they witnessed a cat within the glider's wing, urgently clawing to stay aboard the aircraft.
The pilot discovers the cat shortly after takeoff; and fortunately, all the passengers arrive safely to the basis in the end.
A standard flight until... i still don't know if it got in after the pre flight check or if i missed it. The cat is doing well, she is still our mascot.
Source: Romain Jantot