Former Conservative MSP Mary Scanlon, 71, who represented the Highlands and Islands for many years, appeared in the audience as a punter.
But SNP MP Stewart McDonald questioned why Ms Scanlon was not put on the panel to voice her opinion, and accused her of ‘pretending’ to be an audience member during an appearance in Elgin.
Ms Scanlon spoke about the future of the Conservatives and the need for a UK leader that would unite the party and the country.
The BBC has been accused in the past of bias with the show being forced to defend its vetting process after it emerged that former UKIP candidate Billy Mitchell had appeared on the popular politics show four times.
Deputy First Minister John Swinney of the SNP, Scottish Labour leader Richard Leonard and Edinburgh West MP Christine Jardine of the Liberal Democrats were among those on the show.
But social media users questioned why Ms Scanlon was not chosen as a panellist as other former politicians have been.
Writing on Twitter, Stewart McDonald said: “Why is former Tory MSP Mary Scanlon - 1999 to 2016 - pretending to be an audience punter on #BBCQT?”.
Responding to Mr McDonald, Conservative MSP Edward Mountain said: “I think, as she is no longer an MSP, that she is just a voter. I also know she will have been through the audience vetting process.”
But MSP Jenny Gilruth, also a SNP politician, described it as ‘outrageous’.
She wrote on Twitter: “Why is Mary Scanlon, former Tory MSP, being allowed to ask questions as if she’s a normal punter on #BBCQT? Outrageous.”
And commentator Gerry Hassan said: “The latest #bbcqt audience question:
“Why is Mary Scanlon, Conservative MSP for the Highlands & Islands from 1999-2006 and 2007-2016 seen as a ‘punter’ by the BBC & able to pose as a neutral authority on Tory civil wars?
“Who does the audience selection on this prog? Fire them now.”
Del Edmond added: “This woman was a Tory MSP until 2016.
“Her name is Mary Scanlon. Former MPs and MSPs are regularly on the panel.
“They should NOT be allowed to speak from the audience. It doesn’t reflect society. #bbcqt”.
The application form for Question Time requires prospective guests to say whether they have previously been on the show, and when, and also who they would be most likely to vote for in a General Election.
It also asks how they voted in the EU referendum, and whether they are a member of a political party.
A spokesman for the BBC said: “Question Time does not bar people from its audience because they have held elected office or are political activists.
“There is a selection process to ensure a range of views are heard and last night’s QT audience included supporters of different political parties, including the SNP.”