Glasgow-born Iain Smith, whose movie credits include Cold Mountain, Children of Men, the new Mad Max movie, Fury Road and US series 24, spoke out after Pinewood Shepperton yesterday unveiled plans for a major new four-stage film studio.
The 180,000sq ft complex is to be sited near Cardiff Bay and will be worth £90 million to the Welsh economy.
The homes of the James Bond series, has signed up for at least five years with the Welsh Government for the Pinewood Studio Wales. Ministers have announced a £30m film and TV fund, on which Pinewood will advise.
Film studio officials travelled north to meet with Creative Scotland and Scottish Enterprise last year.
Mr Smith, who is also chairman of the British Film Commission (BFC), said: "The appointment of Pinewood Shepperton to advise on a new Welsh media fund and to operate a new studio facility in Wales unfortunately draws attention to the fact that Scottish Enterprise has been unable to reach a conclusion in almost a year of careful deliberations.
"The Welsh Government in the meantime has seized the opportunity of the moment, just as Northern Ireland did with Game of Thrones."
He added: "The hand to mouth existence of the industry in Scotland has to be improved upon if there is to be any hope of a sustainable commercial and creative infrastructure.
"Hoping that a couple of warehouses will do it, is just plain naive."
Smith said the new Pinewood studio was "absolutely a potential win for Scotland that has been lost through inaction".
The film industry in Scotland has long argued for a facility to be built in Scotland and Scottish Enterprise is due to publish a report on a film studio plan later this month.
Andrew Smith, director of strategy at Pinewood, said: "There certainly were discussions of proposals in and around Glasgow but I don't think they progressed.
"There had been some, but they did not come to fruition."
A Scottish Enterprise source said it would be inaccurate to portray Scotland as "losing out" but a senior figure acknowledged discussions with Pinewood.
David Smith, director of Creative Industries at Scottish Enterprise, said it had met with Pinewood to gather information for its own plans, and added: "Like Wales, we believe there is significant opportunity to grow our film and TV sector.
"This announcement does not alter our belief that Scotland has the opportunity and capacity for this growth.
"We'll be publishing a feasibility report on the production space options for Scotland in the very near future and will be able to say more then."
A Scottish Government spokesman said it is committed to developing screen industry, had met with Pinewood and will publish a report in the near future.