nmap scan trojan physical target

Sorry for not researching this enough myself. I know, and and would love to, and I will. But for now I would like some answers from more knowledgeable people. Is it possible for a device to be showing connected to a wifi point through a Nmap scan without being connected? It’s because I saw some things through a Nmap scan( all strange trojan ports open), but after the source was disconnected physically, it was still showing connected through a Nmap scan. Am I targetting the wrong source, or is this possible? This is not a professional setting. Thanks though!!