Are there any cameras inside a plane?
Yes


AIRCRAFT CABIN SURVEILLANCE SYSTEM
Surveillance system for aircraft interior (2002)
Surveillance Cameras In Aircraft Cabins (2002)



  JetBlue Airways is the first U.S. carrier to get approval from the Federal Aviation Administration to install video cameras on all its airplanes. 
  JetBlue is a successful start-up carrier based at New York's John F. International Kennedy airport. Soon after the Sept. 11 hijackings, the airline installed bullet-proof cockpit doors on all its planes. And it was the first carrier to match all luggage to passengers.
  
  The airline has outfitted one plane with the video surveillance system, and plans to have its 23 other jets equipped with the miniature cameras within the next few months. 
  
  The cameras are positioned to cover the entire cabin. Some are visible, others are hidden so they cannot be tampered with



In-flight surveillance could foil terrorists in the sky (2008)



  The European Union's Security of Aircraft in the Future European Environment (SAFEE) project uses a camera in every passenger's seat, with six wide-angle cameras to survey the aisles. Software then analyses the footage to detect developing terrorist activity or "air-rage" incidents, by tracking passengers' facial expressions.



A350 cabin surveillance contract (2012/2013?)



  KID-Systeme has been selected to supply cabin surveillance equipment for the Airbus A350 XWB family of aircraft. The integrated solution will include both a cockpit door surveillance system (CDSS) and a cabin video monitoring system (CVMS).
  The CDSS provides pilots with a clear view of anyone in the area of the cockpit door, enabling them to take the appropriate action when entry to the cockpit is requested. The CVMS allows both the pilots and the cabin crew to view passengers.