According to Official Guinness Records,
The most people performing 'see no evil, hear no evil, speak no evil' in 24 hours (multiple venues) is 26,204 participants and was achieved by the World Hepatitis Alliance (UK), at 41 venues across the globe, on 28 July 2013.
For a complete list of 2013 records, please visit 2013 Guinness Records in United Kingdom.