In the first few minutes of the movie, as Iceal Hambleton (Gene Hackman) walks towards the helicopter, he carries a golf club in his right hand, and incorrectly salutes the helicopter pilot with his LEFT hand.
In the movie, the aircraft flown by "Bird Dog" was not actually a Cessna O-2 observation aircraft, but was a civilian Cessna 337 Skymaster, painted gray. An O-2 would have multiple windows in the doors and floor to allow visibility of the ground.
When Capt. Clark falls after been shot in the shoulder, the M-16 he is carrying doesn't have a sling and is a stunt rubber replica as the stock flexes when caught between the two men, the M-16 is then picked up by Col. Hambleton and has a sling fixed to it.
When Lt.Col. Hambleton start running through the jungle to be rescued by Capt. Clark, he doesn't carry his hand-made stick. A few moments later he emerges from the jungle sustaining himself again with the stick.
The camera is filming the "pilot" of the Jolly Green Giant as he is flying above the jungle to perform another pass at a rescue attempt of the downed navigation officer. Through the pilot's window is a glimpse of a parking lot with multiple cars, including a blue and a white car very visible through the trees.
When Hambleton calls in the first air strike from the ground, the planes report carrying full loads of "snake and nape". However, the visual shows the planes carrying something along the lines of sparrow missiles. The girth of Snake Eye bombs and Napalm bombs (snake and nape) are easily discernible from the long, slender rocket-like missiles that these planes carried.
The "Jolly Green Giant" helicopter is actually a Siskorsky S-61, a type built for the U.S. Navy. The Siskorsky HH3-F was used by the U.S. Air Force and featured a ramp at the rear of the fuselage. The S-61 did not have a ramp.
When Hambleton ejects from his crippled aircraft, the parachute that opens is a Para-Commander, a sport parachute that never would have been used in an ejector seat. The actual parachute would have been an unslotted 28' diameter white/green/orange parachute with a four-line release system for steering.