Continuity mistake: After Garfield takes treatment at an orphanage, he looks at a dog in a cage and jumps on the counter. In this shot on the counter you can see the comb, a bottle of shampoo and a jug of liquid soap. Look at these things when Garfield says 'But I've got somebody waiting', and you'll see that the comb has changed position on the counter. (00:12:55)
Continuity mistake: When the books fall from the shelf in front of Garfield, there is a pile of books right in front of him. When it cuts, the pile is gone and the books are more scattered. (00:30:40)
Continuity mistake: When Odie comes out on the porch to keep Garfield company, his collar and tags are visible; even more so when he attempts to get back in. But when the shot pulls away to show Odie alone on the steps (before running off after the scooter), his collar is gone. Part of the plot hinges on Jon trying to find Odie, who wasn't wearing his tags.
Continuity mistake: When he is surfing down the stairs, he seemed to have gone further down the building than where he falls out the window.
Continuity mistake: When Garfield is looking for Telegraph Tower, he says it's next to a blue and orange tree. On the Kibbly Kat box however, there is no blue and orange tree on the box, let alone next to the tower.
Continuity mistake: When Garfield is captured by Animal Control, he is put next to Happy's cat. The next time we see him in the cage, he is next to a different cat.
Continuity mistake: In the train station, Dr Liz is wearing white heels. As they get out of the car and embrace, she is now wearing white flats.
Continuity mistake: When Garfield is outside of the house, the dog door shows as green. When Odie is outside it is black. Throughout the movie, the dog door continuously changes color.
Continuity mistake: When Garfield rescues Odie and Happy Chapman picks up Odie he puts the shock collar on him. It then cuts to the dogs howling and then cuts back to Happy Chapman and you can see that the collar is no longer around Odie's neck but in Happy Chapman's hand. It then cuts back to the dogs and then back to Happy Chapman and the collar is back on Odie. He then starts to run and the collar is off again.
Continuity mistake: Garfield has a thumb on his front paws, giving him 5 digits on the bottom of his paws. He is shown leaning on a window and all 5 are making contact with the window as a human hand would. The paw print that Jon finds and recognizes as Garfield's are normal cat prints with only marks from 4 digits. If his paw did have 5 digits as seen in the window, he would have left a 5 toed print.
Continuity mistake: The first time we see Jon pull his Volvo into his driveway, he parks it kinda crooked, the next time we see it, it is parked straight.
Continuity mistake: When Odie first starts to dance at the dog show, Jon stands up, but if you look in the background while Odie is dancing, Jon is sitting down, then a couple of shots later we see him finally sit down.
Continuity mistake: When Garfield jumps on the bed, the sheets swap from slightly wrinkled to very wrinkled, depending on the angle focusing.
Continuity mistake: When they are doing the line up at the pound, there was more than one cat playing Happys cat. When they first put Happys cat down on the floor, you see his back is all black. But when the guard picks him back up he has a white spot on his back. When Happys cat hits the red button, his back is black again. This happens a few more times throughout the movie.
Answer: The song is called "Holla", by the Baha Men (of "Who let the dogs out" fame).