Originally Posted by GothamAlleys
The comic book adaptation fills in the blank showing Jokers goons in the back walking into the cathedral when Jokers with Vicky outside. There are more explanations tho. Either Jokers goons were planted there beforehand to observe (the cathedral would be the best spot) or look out for Batman or police backup, or simply quickly followed Joker in off camera
Fanwank that doesn't even make sense.