Kofi Kingston was supposed to do another one of his famous saves from elimination (akin to Morrison in 2012 and Naomi in 2020), but unfortunately he came down towards the barricade at such an angle his feet hit before he could do what was planned, which was to have him hold on by his knees. This forced the referee to declare him eliminated as there was no way to rescue the spot.
While not shown on screen, the WrestleMania sign was lowered during the Becky Lynch/Doudrop match in order to put out a small fire inside the sign from after the first set of pyros went off following the end of the women's Royal Rumble match. This unfortunately diverted interest in the match from the crowd, especially those who didn't know at first why the sign was lowered. (The sign caught fire again after the men's RR match as well, but by then the crowd was dispersing as the event was over.)
According to attendees at the PPV, people literally started walking out of the stadium as soon as (or soon after) Brock Lesnar's music hit, declaring him the #30 entrant.
Brock Lesnar shattered the record held by Edge for the shortest amount of time a superstar spent in the Royal Rumble match from entry to winning it, being only in there for 2:32. (Edge was in the 2010 match for 7:37.)
Seth Rollins entered his match with Roman Reigns with The Shield's music, and through the crowd like they always did. Coincidentally, eight years earlier at the 2014 Royal Rumble PPV, Seth entered the Royal Rumble match at #2 to The Shield's music and coming through the crowd, as the faction was still together back then.