Organising committee representatives said temporary installations and decorations would be completed in coming days, and coloured fabric covered up pieces that were not quite finished.
Rio de Janeiro will host South America's first ever Olympics in the middle of a state financial crisis, a health scare over the Zika virus, an investigation of corruption on Olympic contracts and impeachment proceedings against suspended President Dilma Rousseff.
On Friday, the World Anti-Doping Agency suspended the credentials of a testing laboratory in Rio de Janeiro for failing to comply with international standards, though it has arranged for testing elsewhere.
The velodrome ceremony was originally scheduled for Saturday but was pushed back a day to give workers more time.
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The city government cancelled its contract with the company constructing the 150 million reais ($45 million) velodrome after the firm filed for bankruptcy protection several weeks ago. A subcontractor stepped in to finish the project.
A test event had to be cancelled in April, though athletes were invited to try out the track over the weekend.
Mayor Eduardo Paes told close associates the velodrome cost him the ability to say the city met all deadlines on Olympic venues.
"We can't say that the velodrome was finished on time, but as I've said with the other projects, it was within budget," Mayor Eduardo Paes told journalists on Sunday.
The city is also scrambling to finish a subway line that would take fans to the Olympic Park.
($1 = 3.37 reais)
(Reporting by Rodrigo Viga Gaier; Writing by Caroline Stauffer; Editing by Phil Berlowitz)
