We took a picture with a celebrity patient... Is that a hippa violation?

Probably not, especially if he agreed to have the picture taken.

Yes, assuming he knew you were taking the photo and allowed it. But there may be hospital rules against doing this, We at a hospital I worked out, often had many famous people at a spine and head injury hospital. We would have lost our job from doing this, from other rules.

Without a written authorization from the "celebrity" this is a HIPAA violation.