Susan Olsen (Cindy) was the only original cast member not to appear in the movie, because she decided to go on her honeymoon in Jamaica. She also found out that Paramount only had to deliver on five of the six "kids," and wanted to pay Olsen the least, which was all the more reason for her to turn down the film.
Though Carol (Florence Henderson) repeatedly reminds Alice (Ann B. Davis) that she is no longer the family's housekeeper, Alice inexplicably turns up in scene after scene donning the iconic blue uniform she always wore on the original series, The Brady Bunch (1969). Most likely purely out of instinct.
When Alice is meeting people at the airport, she initially approaches a young woman, incorrectly believing that she is Cindy, shortly before the real Cindy arrives. This is likely a reference to the fact that Cindy is not played by the actress who originally played her, Susan Olsen.
Mike Lookinland didn't dye his hair brown as he did during the original series, making this the first time Bobby was seen blond.
The film references several plot points of The Voice of Christmas (1969) from the original television series, The Brady Bunch (1969), most notably the scene in which the Brady kids find themselves congregating in the middle of the night on Christmas Eve, drawn together by their shared pain. In the original, they converge around the Christmas tree, whereas in the reunion they commiserate around the kitchen table.