According to pro-football-reference.com, it's the first time (since 1960) that there have been four different players with 3+ receiving TDs on the same day. Four times there were three players who did it on the same day:
9/17/1989 - Henry Ellard, Roy Green, Keith Jackson
11/9/1969 - Fred Biletnikoff, Bob Trumpy, Gene Washington
12/1/1968 - Lance Alworth, Don Maynard, Wendell Tucker
11/6/1960 - Raymond Berry, Tommy McDonald, Sonny Randle