While Terri is speaking to her unexpected guest, a pan is on the cook top containing what are apparently two glass baby bottles inside for sterilization. She returns to the stove and the bottles are on the counter.
When Terri is pulled over by the police officer, Collin's window on the passenger side changes from open, to shut, to halfway rolled down, to shut and then he finally lowers it when Terri leaves the car.
Colin is an escaped convict, he murdered two correctional officers while escaping from state custody. There would be a nation wide manhunt for him, his picture and information would be all over the news and social media sites and there would advisories on the radio in Tennessee, the surrounding states and the whole mid to lower east coast. Alexis, Colin's ex girlfriend would have been notified by the police of his escape and even possible had a police car posted at her house. Yet she is completely surprised when she sees Colin in her house. After Colin murders Alexis he leaves her body where he killed her and then later returns with Terry and her children. It is very unlikely her body laid there undiscovered for such a long period of time, a police officer would have found her body before Colin returned, since she would be someone the cops would be watching because of Colin's escape.
The goof items below may give away important plot points.
When Alexis (Colin's girlfriend) grabs her phone and runs away from Colin, she has a blackberry phone with a built in keyboard. When Terri finds Alexis's cell phone next to her dead body, under the bed, it's an Android phone.
Colin seeing Alexis with another man is the reason he kills her out of revenge, along with the fact that he found a note from that man. It's revealed at the end that Javier is the man Alexis had been seeing. That's why Colin went after Terry, who was Javier's wife. But Javier is not the man we see Alexis with at all in the beginning.