Temple is examining charts in his office when Arden comes in to invite him back to the farm where the meteors fell. When the wall is shown again, a large new chart of the moon has appeared.
The first time Dr. Temple visits the petrol station, as the blonde attendant stands alongside his jalopy flirting with him, Temple's left hand is on/off the steering wheel between shots.
While Stillwell and Curtis are having their discussion in the jalopy, the blue screen background is reflected on the car making it appear as though the hood is transparent and the countryside is seen through it and Stillwell.
The main character's reaction shot when he leaves the gas station for the first time (devilish smile from the car, closeup) is re-used later on in the film, when he leaves the gas station for the second time.
After the aliens land on Earth and start taking over human bodies it would take great resources and a lot of time, perhaps a decade or more, to construct the underground installation and moon rocket. However the characters show no sign of aging, nor is there evidence of construction at the farm.
The 'solid silver mind control protection device' that Farge smushes into the bikers helmet bends in such a fashion as to confirm that it is in fact a plastic colander sprayed silver.
After Dr Curtis Temple is first captured by the invaders there are many close ups of his cell door, where you can clearly see the pencil lines the set makers used to position the 'rivets'.