The 23-year-old vanished while on a night out with friends on 24 September in Bury St Edmunds, Suffolk.
Suffolk Police officers combing through CCTV footage have released stills of three people who have yet to be traced.
Mr Mckeague, from Dunfermline in Fife, was last seen walking alone in Bury St Edmunds at about 03:25 BST.
He walked into a dead-end area known as the "horseshoe" and was not seen again.
Following a previous appeal, police still need to trace two people shown on CCTV - a cyclist and an older man.
A name had been given for the older man, but this person has since been traced and he was not the man in the image.
A third picture has also been released. It is a better image of a potential witness, believed to have featured in pictures previously released on 8 December.
All of the footage was filmed in Bury St Edmunds town centre between 03.15 and 05:20 BST.
Police said the vast majority of people in the area who were captured on CCTV had been identified, traced and spoken to.
The three people in the images were the last seen on foot in the area who have yet to be traced.
Det Supt Katie Elliott said police had worked through information in a "logical way".
She added police have not received any information as yet from an intelligence services company employed by Mr Mckeague's family, but anything passed on by them would be considered as part of the ongoing inquiry.
New images have been released of three potential witnesses to the disappearance of missing RAF serviceman Corrie Mckeague.