All of the KGB characters shown in uniform at the beginning of the film are "out of uniform." Although Borzov, Bronson's character, and the others are clearly meant to be in the KGB, the uniforms they wear are trimmed in red, the color of the regular Soviet Army, not the KGB. During the era of the film KGB uniforms were trimmed in Royal Blue. Also, the uniforms in the film lack the distinctive "Sword and Shield" patch worn by KGB officers on their jacket and coat sleeves.
The film title is a transliteration of the Russian word for "telephone". The letter "o" is pronounced in Russian like it is in the English word telephone, although the KGB in the film pronounce it incorrectly (rhyming with "telethon".)
Generals and officers in Soviet army didn't have black trousers and green ties as part of their official uniform. In fact black ties and khaki trousers were the only colors available for use.
The helicopter sent by the KGB to retrieve Borzov from the hockey practice in Moscow is a French Alouette, which was never used by the USSR.
When Hassler's (Ed Bakey) helicopter is approaching the Appalachicola Naval Communications Station, the station's "radar" display shows the blip representing the helicopter move before, and after the the rotational scan; not when it is hit by the beam, as in reality.
No foreign cars were allowed to be used by KGB officials back in 1970s. Instead of filmed Mercedes Pullman KGB general should've been driven in ZIL or Volga.
KGB officers and insignias are quite messy (stars and stripes are of not correct size etc.)
Sergeant in KGB office is pulling out unloaded gun to shoot everyone in the room. The gun is revolver which used to be Soviet Army official gun but was changed soon after WWII to Makarov (clip type). Hence quite unlikely general would have such an obsolete weapon in his office minding all the security and control in KGB.
When Dalchimsky is watching Hassler take off, it is obviously from high vantage point. During his flight, he passes some very prominent hills. Florida is very flat with the area around Apalachicola being only a few tens of feet above sea level.