Pictures from the "What If..." set, days 8 and 9

"We shot the film with two cameras, which meant that at certain times, one of the cameras could be taken away for "establishing shots" and "B-roll." Establishing shots are usually scenery shots or shots of locations that don't require any actors. B-roll involves random shots of activity that again, doesn't require lead actors."

You can view the whole gallery of pictures on the Jenkins-Entertainment blog.