The acclaimed movie won Best Picture at Hollywood's biggest prizegiving last month (Feb11), as well as Oscars for star Colin Firth, director Tom Hooper and screenwriter David Seidler.
Egan and co-producer Gareth Unwin headed to their rented house in Tinseltown to celebrate a stellar night, and his 15-month-old daughter, Lara, was handed the golden statue to pose for a picture.
But the party came to an abrupt halt when the tot dropped the prized accolade on the cement pavement, knocking off a huge chunk of gold plating.
Egan tells Britain's Daily Mail, "Like everyone else I was celebrating off in one corner of the garden with some friends when I saw my daughter looking very cute with the Oscar having her picture taken.
"And then I saw that horrific moment where the statue just fell and it didn't fall on the grass - it fell on the concrete. The horror was evident on everyone's face as they all went, 'Oh s**t.' We rushed over to look at the damage and saw a bashed head and gold plating fallen off the chest, a damaged shoulder and a dented stand.
"My first thought was 'Oh god, what is that going to look like on the mantelpiece! It is a thing of beauty and my daughter had destroyed it, albeit unwittingly. We were all terrified."
However, the problem was quickly rectified by a visit to the Academy offices in Beverly Hills the following day.
Egan adds, "They gave us a brand spanking new Oscar within minutes after a lady wearing gloves took our damaged one away."