My baby rolled off the bed. He cried for a minute but now is acting normal & laughing & playing. Should I take him to the er?

Fall. A fall from a typical bed is only 2-3 feet. If the baby has no sign of injury (swelling, bruising) and is playing happily with all 4 extremities, you don't need to go to the er. You do want to watch him closely so that if something changes, you can get him checked.