New Year's Eve revellers were taken back in time for a moment during Monday's fireworks after a typo was projected onto the Sydney Harbour Bridge.

The typo on the pylon last night, Credit:Andrew Hornery

"Happy New Year 2018" lit up one of the bridge's pylons, with many taking to social media to point out the gaffe.

The error occurred during the midnight fireworks, when an estimated 1 million people watched on the edge of Sydney Harbour, and a further 1 billion looked on worldwide.

Only a select few though were clever enough to recognise the mistake, with one Twitter user calling it a "great error".