During the day on twitter, a few were saying "it must be invisible" and no drone can fly for that long"
Even though 67 reported isghtings had been made, police had not been able to acquire any footage.
The airport has spent £5m since Wednesday on new equipment and technology to prevent copycat attacks.
The revelation by Detective Chief Superintendent Jason Tingley came after two people were arrested, but later released without charge.
Asked about speculation there never was a drone, he said: “Of course, that’s a possibility. We are working with human beings saying they have seen something.
Now police have been forced to defend their investigation amid suspicions the 67 reported drone sightings were all false alarms.
Police do not have any footage of the flying devices at the airfield and are relying on accounts from witnesses and the discovery of a damaged device at the edge of the airport but could have been there for weeks. This is now being forensically examined.
The army were called in to help with the chaos at London's Gatwick Airport.
The arrests made on Friday night were the result of a tip-off from a member of the public.
He insisted the investigation was not “back to square one” and added: “We have a number of lines of enquiry and persons of interest. We are still progressing those lines of enquiry, including house-to-house enquiries around the sightings of the drone.”
Around 1,000 flights were cancelled or diverted after drones were spotted inside the perimeter of the UK’s second biggest airport on Wednesday and approximately 140,000 passengers were affected over a three day period.
Labour has called for an independent inquiry after accusing the government of failing to act on the risks posed by drones at Gatwick.
Shadow transport secretary Andy McDonald claimed there were missed opportunities to prevent the airport from coming under such an attack.
“The government was repeatedly warned about the risks posed by drones to aviation but failed to act,” he said.
Additional reporting by Press Association