Visible crew/equipment: After Batman and Catwoman's mistletoe banter, a wire can be seen attached to his back as he glides off the rooftop. (01:20:15)
Visible crew/equipment: When the large present drives out into the middle of the Christmas procession, as the lid of the gift springs up, a long white wire can be see attached to the lid, which wasn't there beforehand. (00:11:30)
Visible crew/equipment: When the Penguin dies and the penguins slide him into the water you can see the slide-board he was laying on slip out ahead of him under the water. It is also very clear that the penguins aren't even touching him as they pull him into the water. (01:53:00)
Visible crew/equipment: After the scene where Selina shocks the clown henchman with the taser, it cuts to the Mayor thanking Batman. As they walk down off of the walkway and continue down the road, if you look on the floor behind Batman you can see black camera tracks on the floor of the raised, bridge walkway. (00:16:15)
Visible crew/equipment: After Selina tasers the henchman, it cuts to the Mayor thanking Batman. As the camera pans past Batman, a noticeable shadow is cast on him. (00:16:15)
Visible crew/equipment: A wire can be seen attached to Oswald Cobblepot as his penguins slide him into the water after he dies.
Visible crew/equipment: After the policemen shoot Batman, he falls backwards and slides down the circular ledge. When it cuts to a close-up of him dropping on his back to the ground, the hand of the crewmember placing him down to the ground is visible. (01:15:25)
Visible crew/equipment: When the monkey jumps onto the cage in which Max Schrek is prisoner, you can see a cable clipped to its jacket it is wearing. (01:46:00)
Answer: Nothing was stopping them. After Penguin's true nature was revealed, they most likely started searching the entire sewer system but couldn't find where his lair actually was so they had no choice but to give up.