Straker is shot in the hand by Croxley. Later on, Straker and Freeman share a drink back at headquarters and Straker has no visible injury to his hand.
During the final scene the diameter of the muzzle at the end of Croxley's gun varies a lot.
Onscreen the "2 hour" meeting at the house with Croxley from 10pm to midnight passes far too quickly, with nothing to suggest that offscreen very much occurred that simply wasn't shown. There is a cut just before Croxley places the lamp on the table but then he is shown again just after walking away from the table having done that.
When the U.F.O. explodes, as viewed behind the wind screen of the Mobile, pieces of the U.F.O. fly behind the wind screen, indicating that the wind screen was added in.
Croxley gets into his car in Britain and it is left hand drive (the futuristic series always indicates that Britain has changed its driving convention in the future to that of The US etc) - but as he pulls into a carpark a red car which is parked in the background has the normal right hand drive steering wheel - revealing that it was filmed in 1970 in Britain.
The ending credits list Douglas Wilmer's character as Dr. Ward, but earlier scenes show a plaque outside the doctor's office inscribed with "Dr. A. Brunner".
Stanley McGeagh played the SHADO security man, but the end credits list him as Stanley McGeogh.
At 7m 50s a video link is established to Moonbase. There should be a 2.6s round trip delay in the audio/visual , but there is no delay.
When relaying the thoughts of the aliens who plunder Earth, Croxley says - "Our national resources are exhausted." instead of " Our natural resources are exhausted."