Whilst flying the helicopter prior to, during and after rescuing Billy from the airstrip 'Tango 7', the yellow paint on the interior framing of the cockpit door to Ryack's right appears and disappears from shot to shot.
Air America's plane side number 238 passes by in the background when Senator Davenport arrives at the airport in Laos when at the same time it is being flown by Ryack and Covington to the hill top air strip where they meet Ryack's brother in law.
During and shortly after the title sequence after the C123 is hit by the peasant farmer's lucky rifle shot you see the starboard engine being feathered prior to being shut down. When you next see it after the Nixon TV interview both engines appear to be running normally just before the starboard engine explodes
When the C123 comes to a halt after the crash at the Tango 7 Airstrip, a brief shot shows the main fuselage segment with the wrecked remains of the smaller blue/white plane that is crashed into it much later in the film.
Near the end of the movie while Nancy Travis (Corinne) is waiting to load the villagers she is wearing a white shirt with an OD over shirt unbuttoned. Once she is on the plane, only a minute later, she is wearing a tan colored shirt.
When the right engine was hit by ground fire and was said to have lost oil pressure, it is doubtful that thrust could be maintained. With the extent of damage requiring fire extinguishers, it is most likely that it would have been feathered. This did not occur and during the landing sequence, it can clearly be seen that this engine is developing its usual thrust, the props both appearing to be turning as they would be when synchronized. Also if thrust were lost on that engine, a large amount of left rudder with about 3 degrees elevation of bank on the dead engine side would be required and none of this is seen in the film.
In opening scenes a C-123 is shown dropping cargo from it lowered gate in the tail end of the fuselage. In the next camera scene it is shown nearing the ground and going through the roof of a hut. It is shown going straight down. In the case of an air drop, all such cargo would be dropping at an angle, and not straight down.
Gene's necklace appears to be defying gravity at one point, but the helicopter is pointed straight down; the camera is also twisted, which makes the characters appear to be upside down instead of at a 90 degree angle.
When Billy is haranguing the truck driver on the freeway, the drive hears Billy over the radio. However, we clearly here the truck driver over the helicopter's radio. It would be nearly impossible to hear the truck driver over the helicopter noise, even standing next to him. Billy wouldn't be able to hear him at all in cockpit, much less have his microphone pick up the driver's cursing with almost no background noise.