After she transforms into a cat, April loses her tail in a number of shots.
After Leonardo cuts the control collar off of April, he turns into Donatello. He even speaks with Donatello's voice.
In the POV shot of April going behind the news van when Vernon says "My, aren't we grumpy," the back of the van has one rectangular window on the rear end and no doors. In the next shot when April is pulling out her turtle com, the back of the van has rear doors and windows.
When the cat jumps onto the transporter's control panel, he walks over to the yellow colored set of buttons on the upper side of the panel. In the next shot where he steps onto the button, which activates the transporter device, the buttons are orange. Then in the next shot of the cat on the control panel, his front paws are on the yellow buttons and his back feet are on the orange buttons and he's changed positions on the control panel.
The pictures April took had the cat in each one but April new photographed the cat.
When Erma is talking with Leonardo on the communicator the image on the communicator is Raphael.