Elevons are like "flaps" on the trailing edge of the wings. They move up and down and provide pitch and roll control. There is also a body flap in the center for pitch trim. Take a good look at a shuttle picture and you will see them. They are split in two parts for structural reasons: Inboard and Outboard.
Av Week asking if it's possible to have a main gear door not completely closed without anyone knowing about it.
Dittimore: NO.
snopercod: I agree, having seen these wheel wells and doors up close and personal. They are mechanically latched shut and CAN'T open without massive mechanical failure.