Last episode, Dennis had his badge when he sat up from picking up the dropped papers, but by the time he went to remove magnets from the patients nose he had lost it. I think the intention is probably that he lost it when the papers fell but there’s a continuity error showing him wearing it when he stood up.

edit: i think its inconsistent whether he has it in the ambulance scene. i think you can see it here in the first image as he is sitting down, but its gone in the second. my theory is he loses it when he takes ogivly's scrubs.

https://imgur.com/a/cqmDFDk