President and CEO Stuart Murray said they had intended to have all 11 galleries open by Saturday, but that isn't possible. Only five galleries will be done when the museum welcomes the public.
People will only be able to tour the museum through a choice of two 90-minute guided tours until November and are encouraged to buy their tickets online in advance.
"There are some elements that we thought would be here that just are not here," Murray said Wednesday without elaborating on what those are.
"There's a lot of moving parts in a big project of this nature."
The museum officially opened Sept. 19, with political speeches and performance. There were protests outside the ceremony calling for government action on missing and murdered aboriginal women, living conditions on reserves and other issues.
At the time, officials said they expected all galleries in the $351-million museum to be open on time with the exception of a few "finishing touches." But Murray said it soon became clear that wouldn't be possible.
He said he had a choice to close the museum for a couple of weeks until all the exhibits were done or open as scheduled with only a few galleries.
"We felt it was best that we open on the 27th (and) that we give a very robust, inspiring opportunity, whether it's through the architecture of the building or whether it's through the tours that go into the galleries for 90 minutes. We believe that's the best way."
People whose stories make up some of the exhibits have been told to delay their visits to the museum until the galleries are finished in November, Murray said. Although officials said the museum's grand opening garnered international attention, Murray said he doesn't think the museum's reputation will be tarnished because it isn't finished yet.
"We understand that there's a lot of expectation on us," he said. "I take responsibility. We talked about opening on the 27th and we're not there."
The public can go on two tours of the museum starting Saturday — one which highlights the building's architecture and the other which explores the galleries, including "What Are Human Rights?" and "Indigenous Perspectives."
Both tours include a trip up the "Tower of Hope," a glass observation tower with views of Winnipeg and its two converging rivers. Research shows most people spend about 90 minutes in a museum so the tours are tailored to that attention span, Murray said.
The tours are $10 for adults — less than the regular admission of $15 the museum will charge when all galleries are up and running.
"We're going to be able to offer you a spectacular visitor experience and our staff are all charged up," said June Creelman, the museum's director of learning and programming.
When the museum opens in its entirety, it will house a copy of the Bill of Rights signed by former prime minister John Diefenbaker in 1960, a 1763 royal proclamation by King George III that established protocols for relationships with First Nations and head-tax certificates paid for by Chinese immigrants around the start of the 20th century.