Saga of a Star World (1) - S1-E1
Revealing mistake: In the second shot showing the fleet of Battlestars (from the port side and slightly behind), two ghostly images fly in formation with the three Battlestars shown. They are just above the closest ship (where the narrow middle meets the larger rear section). It seems that the shot may have originally contained 5 ships and an attempt was made to 'remove' the most distant two, leaving the "ghosts". (00:02:45)
Revealing mistake: When the Hulk throws the large bell to break the tower's wall during his second transformation, we can see three cables attached to the bell, most likely used to guide its trajectory.