Although he doesn't have his own Twitter page, McCaw posed for a selfie which was tweeted out on the Queen's official Twitter page.
He also noted how fortunate he was to be able to attend the exclusive reception.
"When I first came to Buckingham Palace and met the Queen, my grandparents were just absolutely blown away. There are heaps of people standing outside who would love to have a look around so we're pretty lucky to go do that."
Other players at the event included Stephen Moore of Australia, Greig Laidlaw of Scotland, Mike Stanley of Manu Samoa, James Haskell of England and Bryan Habana of the Springboks, as well as All Blacks coach Steve Hansen.
Hansen enjoyed his time with the royal family, who wished the All Blacks good luck for the rest of the World Cup.
"It's always nice to come here, they're a lovely family right from the top to the bottom, they're just normal people really when you get to meet them. In these circumstances, obviously they're in the limelight all the time, which is difficult I guess, but when you meet them one on one they're lovely people.
"It was a nice occasion, it's good to catch up with the other coaches and players and enjoy the evening."
The Webb Ellis Cup also made a special appearance at the event, taking "pride of place" at the Buckingham Palace ballroom.
England Rugby fan Prince Harry - who is also vice patron of the RFU and honorary president of England 2015 - gave a speech describing this years' competition as "one of the most competitive and entertaining World Cups ever".
"This evening, we would like to thank all of you for making England 2015 such a successful and enjoyable tournament for everybody," he said.
"You are helping inspire children of all backgrounds to get involved with the game the game we all love."
Prince Harry and his brother the Duke of Cambridge have made several appearances at Rugby World Cup games - they even attended the Wales v England clash, while each cheering for different sides.
- nzherald.co.nz
