In The Best Night Ever, "Caesar" appears numerous times in and around the castle. During At the Gala, he is part of Rarity's, Rainbow Dash's, and Pinkie Pie's choirs. In an attempt to impress Spitfire and Soarin, Rainbow Dash knocks "Caesar" into the air and then catches him on her back. This fails to grab the Wonderbolts' attention, however, and she throws "Caesar" off, leaving him confused.
03:48 - outside the castle with Lyrica Lilac and "Royal Ribbon"; 04:20 ~ 06:55 - several times during At the Gala; 07:38 ~ 08:20 - in the castle; 08:52 - near Applejack's stand; 09:18 ~ 10:00 - in the Wonderbolts' VIP section; 10:23 ~ 10:47 - in the ballroom; 11:44 - talking with Lyrica Lilac; 12:07 ~ 12:32 - walking up the castle foyer steps; 12:40 - passing by Applejack's stand; 12:47 - in the ballroom with "Royal Ribbon"; 14:10 ~ 14:28 - being thrown and caught by Rainbow Dash; 15:16 - shocked by Pinkie Pie on stage; 15:29 - on the castle foyer steps again; 18:19 ~ 19:30 - in the ballroom, watching as the Gala is slowly ruined
05:52 ~ 05:59 - during This Day Aria, Part 2 (with several duplicates); 06:17 ~ 09:30 - at the first wedding and during Queen Chrysalis' reveal; 17:34 ~ 18:35 - at the second wedding; 18:59 - in the crowd of ponies (with several duplicates); 19:43 ~ 20:26 - at the wedding reception (with several duplicates); 20:40 - outside the castle