Revealing mistake: When Billy lies dead in the morgue and the President fixes his hair while saying, "That's better." we can see Billy's throat move as he swallows.
Revealing mistake: When you see Chief Tyrol leaving the camp on the Algea planet, one of the shots where he wanders around before finding the temple of the five, you can see part of the suburbs of Kamloops in BC with cars driving on the road. (00:08:27)
Revealing mistake: After Dualla shoots herself, Gaeta hobbles back into the room. While the effects people made sure his real lower leg was erased from view behind his upper leg, they forgot to remove the shadow of the lower leg being cast upon the steel floor. The shot then changes away and returns to find the shadow has now been fixed the second time we see it.
Revealing mistake: Just after Tigh announces that Centurions will be "pouring in at platoon strength", the next shot shows those Centurions marching though the Galactica's halls. None of them are casting shadows despite the various nearby light sources that should be causing such shadows. This is most obvious looking at their feet.
Answer: The original BSG has something of a complex version history. Several versions exist, but the rationale behind what you're referring to is as follows. BSG, before anything else, was a TV series - the 'pilot episode' was a three-part tale called "Saga of a Star World". In that three-parter, a last-minute alteration to the script meant that Baltar was ultimately spared execution, because Glen A. Larson, the series producer, decided that he liked the Baltar character enough to keep him around for the rest of the series. The theatrical version, which was edited down from the three-parter and was shown in some countries before the US TV broadcast, lost quite a number of scenes, including the one where Baltar is spared. The real continuity of the series can only be found in the TV version - the movies, all of which were created by editing together existing episodes, miss out scenes leading to such apparent continuity errors.
Tailkinker ★