Among the events listed on the Simuls page is the one given by Paul Keres at Trinity on December 2nd 1962, where he played 24, drew two, and lost one, to Tony Dennehy.
That the loss is not recorded in Big Database 2012 is perhaps not surprising, since they don’t really go in for games from simuls (even though they have–stop me if I’ve mentioned this before–5,000,000+ games). But it’s a little surprising that it’s not listed in the ICU games archive either. The game is available, courtesy of A.A. Luce’s very interesting booklet A History of Dublin Chess Club (Dublin, c. 1965), and here it is.
As far as I can determine on a quick play-through (these days I try to avoid using engines if I can avoid it, on the principle that they encourage passivity) the diagrammed position is where it all starts to go pear-shaped for Keres. This is one of those games where the winner hopes his opponent doesn’t resign, as the situation becomes more and more spectacular.
1. d4 Nf6 2. c4 g6 3. g3 Bg7 4. Bg2 O-O 5. e4 d6 6. Ne2 c5 7. O-O Nc6 8. d5 Na5 9. Qc2 a6 10. a4 Rb8 11. Bd2 b6 12. f4 e6 (diagram) 13. e5? dxe5 14. fxe5 Ng4 15. Nf4 Nxe5 16. dxe6 fxe6 17. Bxa5 bxa5 18. Nc3 Nxc4 19. Qe2 Ne3 20. Rfe1 Bd4 21. Kh1 g5 22. Nh5 Nxg2 23. Qxg2 Rf2 24. Qh3 Rbxb2 25. Rad1 e5 26. g4 Bxg4 27. Rxd4 Qa8+