For a sequence that showed the Cylons attacking Earth, the producers used footage from Earthquake (1974) and superimposed Cylon fighters firing and causing the destruction in the sequence. Thus they managed to create a spectacular sequence on a tiny budget.
Well, how did you like that?
Jamie Hamilton: Don't bother me, I'm praying.
At the beginning of the series, the Galactica arrives at Earth in the year 1980. It is said by Adama that their voyage has taken 30 years which means that the events of Battlestar Galactica (1978) took place around 1950 in Earth time. However, at the very end of the original series (in the episode "The Hand of God"), the Galactica receives a television transmission that shows the 1969 Apollo moon landing. Since the fleet's journey to Earth had only started a few months prior, it means that the events of Battlestar Galactica (1978) must have taken place at least in the late 1960s Earth time. In fact it would be at least in the 1970s since television signals travel at the speed of light and the Galactica was obviously far more than a light year away from Earth at the time they received the transmission.
Several episodes end with the disclaimer: "The United States Air Force stopped investigating UFOs in 1969. After 22 years, they found no evidence of extra-terrestrial visits and no threat to national security." This is due to the series featuring an Air Force division dedicated to looking for UFOs.
The first episode was edited together with footage from two unrelated episodes to form the TV movie Conquest of Earth (1984) (TV) for broadcast in the UK.