The 1967 Referendum did not make Australian Aboriginals citizens of Australia
Australian Aboriginals were citizens from 1948 when the concept of Australian citizenship began (prior to this, we were British subjects who happened to live in Australia.)
The 1967 Referendum did two things:
Empowered the Commonwealth to make laws for Aboriginal people living in the various states by removing the exception from Section 51, subsection xxxvi - the "race power", that prohibited it.
Section 122 allows the Commonwealth to legislate with regards to all matters in the territories.
Required the inclusion of Aboriginal people in the "reckoning the numbers of the people of the Commonwealth, or of a State or other part of the Commonwealth" by repealing Section 127 entirely.
This odd phrasing relates to Section 24, which establishes the rules around the number of members of the House of Reps and their apportionment between the states.
There's a lot of myth around the '67 Referendum, some of which was intentionally created at the time by the Yes campaign, and a lot of which has occurred since. This SBS Radio report talks about how while it was technically true that all Aboriginal Australians had been able to vote since 1962 across the country and in most states/colonies had been since the 1850s (including for Commonwealth parliament), the perception was that they weren't welcome to - and indeed it wasn't until the 1980s when it became compulsory for Aboriginal people to vote as it has been for other voters since 1918.
The referendum was more of a watershed moment where the rest of the country stood up around said that it was not acceptable the way we had been treating the Aboriginal and Torres Strait Islander community than a magical moment when rights were granted - the Stolen Generations removals continued into the 1970s in some states, for example!
The premise of your question is based on bad information.
The 1967 referendum didn't do much of what has been implied by media publicity over the years. It posed a question to count Indigenous Australians in the national census and to remove or alter as needed text in the Australian Constitution relating to the legal status of Australian Aboriginals.
Prior to 1949, there was no Australian citizenship, regardless of one's skin colour, but rather naturalised Australian resident. All Australian born residents were considered to be British subjects prior to Januray 26 1949. Passports issued by Australia included the words "British Passport" until 1967 (I don't believe there is a connection to the 1967 referendum).
Given that Aboriginal Australians served in the military in both world wars, and traveled overseas, they would certainly have been able to obtain passports to do so. The problem was that other legislation frequently made it difficult to do so by restricting the means one could save some money to put towards such a trip. Also, Aboriginal Australians started gaining rights that white Australia took for granted shortly after WW2 so far as I am aware when Aboriginal military veterans gained the right to vote, which was extended to other Aboriginal Australians at various points after 1949 and before 1967. In the earlier access points, there were always conditions placed on the new rights, even the one that granted Aboriginal veterans voting rights. But ultimately (with one notable exception I can find - the 1967 Australian Referendum) access to voting rights for Australian Aboriginals came in with the Commonwealth Electoral Act 1962, followed by a 1983 amendment that added our infamous compulsory voting requirement to their voting rights.
TL;DR - yes, Australian Aboriginals could get a passport and travel overseas prior to 1967. The referendum had nothing to do with that right, since all of us, white and Aboriginal alike, were British subjects prior to 1949.