When Evie manages to eavesdrop on one of Tina's phone calls from Ray, she covers the mouthpiece of the phone with a Grey t-shirt. In the next shot it is a black and pink floral shirt.
Ray has a cigarette tucked behind his right ear while talking to Tina about going back to football. In the very next shot the cigarette has disappeared. In the next shot it is there again.
When the male doctor examines Tina's belly, you can see the white pillow just before he brings down her gown.
When Caleb is born, his umbilical cord is not attached. After it is 'cut' there is no clip or remaining piece on his navel, it's completely bare.
Tina's little sister says she wants a sister that's famous for something other than being "pregnant at 14". Tina is 15, not 14. It's even the name of the movie.
Mike visible in the daycare scene shortly after Rachel Spangler decides to move in with her dad.