SINGAPORE - The committee in charge of this year's National Day Parade (NDP) is investigating a hitch in the otherwise smooth sailings of Tuesday's (Aug 9) celebrations.

The National Stadium's domed roof, which lit the night sky with the Singapore flag during the previews, failed to do so during Tuesday's fireworks-filled finale, Today newspaper reported on Thursday (Aug 11).

"The Singapore flag was not projected onto the roof of the National Stadium during the pledge-taking and singing of the National Anthem at the end of the National Day Parade, and we are in the process of ascertaining the cause," the committee said in response to media queries.

"Celebrations still went on smoothly, and the NDP 2016 Executive Committee is heartened by the spirit of Singaporeans both at the National Stadium and at home celebrating our nation's 51st birthday," it added.

The stadium, located within the Sports Hub, has a retractable roof made of a lightweight and weather-resistant material that doubles as a projector screen on both sides.

This year's parade marked a return to the National Stadium after a decade, and packed a full house of 55,000 spectators.

The closed roof meant that favourites like the parachuting Red Lions and fighter jet displays were a no show this year, but it also allowed for aerial performances and suspended props.

This year's parade, themed Building Our Singapore Of Tomorrow, featured six acts that travelled from Singapore's past to its dreams of the future.