Deliberate mistake: When Penny is loaded onto the ambulance at the end, her gurney is rolled straight in. This is wrong, the paramedics will collapse the wheels and slide the gurney into locks to hold it still during the drive. It was done this way since Mittens and Rhino were hiding in the collapsible section.
Deliberate mistake: When the song comes on showing the three travelling across the U.S. on the map, it has them in the bed of the dumptruck, on top of a dirt pile going across 3 states. A dumptruck wouldn't be travelling that far with a load of dirt that can be gotten in any state.
Answer: When Penny is printing "LOST DOG" flyers, the last 4 digits of the phone number on the copier are: 8423. This makes the number (877) 504-8423. 877-504-8423 is a number reserved by ABC for movies and TV series. Calling it will provide a short tape recorded message about how fake it is.