When Cara walks into the grocery store, a voice is heard over the PA that says that the store will be closing in fifteen minutes. Approximately three seconds prior, Cara passes under a sign that says the grocery store is open 24 hours.
Walker is feeding the baby a bottle when Alex says that she should burp the baby. So she takes him and begins to burp him. But when Walker puts the bottle down, you can clearly see that it is almost completely full, meaning he had just begun the feeding. At that point there would have been absolutely no reason for Alex to burp him yet.