Actually, there were references to both the Doctor and UNIT in this episode, and even passing mentions of the Silurians and the Racnoss. But none of them were essential — sort of like half the episodes of "Miracle Day".

It's one of the odd differences between the way Jack is portrayed on Torchwood and on Doctor Who: on Who, he flirts with everybody, and makes remarks about his past which make it clear that he'll screw anybody and anything, but since Who is at most PG-rated, we never see him doing anything. But in Torchwood, Jack is…