The committee in charge of this year's National Day Parade (NDP) is investigating a glitch in an event which otherwise ran smoothly.

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 yesterday.

"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 told The Straits Times.

"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."

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 did allow for aerial performances and suspended props.

Themed Building Our Singapore Of Tomorrow, the parade featured six acts with performances that showcased Singapore's past and its dreams of the future.