During one of playoffs last weekend officials working the game appeared to confer with alternate officials standing on sideline: is this allowed? –Stephen U.
Most certainly. The alternate officials all have specific roles and one of them is to be in contact with the replay booth and the on-site supervisor.
If there is a major foul-up on the field, as there was with the spotting of the ball in the Denver – San Diego game, those upstairs will communicate with the Alternate Officials on the sideline and they, in turn, will communicate with the on-field officials.
The goal is, after all, to get things right and to use any mechanism that is available to do so.