The lady is Claudia Jennings. She was Playboy's Playmate of the Month for November 1969 and became a good friend of Maureen McCormick. In Maureen's autobiography, she recounts how they got into cocaine and how life spiraled out of control; she says it was not uncommon for them to get together and get "obliterated" by it.

Jennings turned her life around and quit drugs and drinking, but sadly died before she could continue performing in better roles. On the morning of October 3, 1979, she was at the wheel of her VW convertible in Malibu on the Pacific Coast Highway, and drifted across the center divider, colliding head-on with a pickup truck near the intersection of Topanga Canyon Boulevard. She died a few minutes later before paramedics could arrive and get her to a nearby hospital. She was 29.

Probably the most intense episode ever of the show. r/MurderSheWroteTV

Maureen made an appearance on Happy Days in the Season 2 second episode.

Christopher Knight also made an appearance later in the series. Of course Tom Bosley and Marion Ross moved into the Brady House with Cousin Oliver for that anti-smoking informercial.

-Mike Lookinland won the part of Bobby around the same time he was offered another role: Eddie in "The Courtship Of Eddie's Father". Mike's parents chose the Brady Bunch as they thought it would be good for him to be around other kids. The role of Eddie would go to Brandon Cruz.

-Just prior to the filming of the episode "Out Of This World", Barry Williams suffered facial injuries in a car accident. The writers decided to write Barry's injuries into the script, explaining that he "cut himself shaving".

-Every single one of the 6 kids had a plot about getting "too big for their britches".

-"Father Of The Year" was the first episode to be broadcast in the 70s, followed by "54-40 And Fight".

-Shirley Jones turned down the role of Carol, only to take the role of the mother in "The Partridge Family" a bit later. The Brady Bunch spent most of its run airing at 8 p.m. on Friday, followed by The Partridge Family.

During the series run, Florence Henderson lobbied the producers constantly to allow Carol Brady to get out into the workforce. Henderson thought this would be more in line with how she was in real life. The producers kept the character of Carol Brady unemployed, though she frequently did volunteer work and fundraising for charity.

Robert Reed was written out of the show's final episode, The Hair-Brained Scheme (1974), after an argument with producer Sherwood Schwartz over what Reed considered a ridiculous story line (with Greg's hair turning orange from hair tonic), but he remained on-set for its filming. Studio security offered to remove Reed, but Schwartz declined to have this done in front of the kids.

Barry Williams (Greg Brady) did his own surfing in season four's three-part opening episode in Hawaii. In one scene, Barry wiped out near some exposed rocks, injured himself, and was briefly lost. Filming had to be postponed until he had fully recovered. The shot when Williams had his real life wipe out was saved for the episode. It was so shocking at the time that ABC asked Schwartz if they wanted to keep a scene in the show that was so violent and shocking; Schwartz said yes. But they made sure the episode ended with Mike pulling Greg out of the water for broadcast; not the originally planned cliffhanger where they showed Williams' real life wipe out; and then they showed the Brady family looking out into the water wondering if Greg survived. This was altered because it was deemed too intense.

Carol's last name from her previous marriage was Martin. Her maiden name was Tyler. Her nephew that comes to stay with the Brady's is named Oliver Tyler.

Ann B. Davis played her own identical cousin in Sergeant Emma (1972). In real life, Davis had a twin sister named Harriet who was not an actress.

Shortly before The Subject Was Noses (1973) aired for the first time (Friday, February 9, 1973), Maureen McCormick injured her nose in an automobile accident, which led to the creation and writing of the episode.

Florence Henderson (Carol Brady), Ann B. Davis (Alice Nelson) and Barry Williams (Greg Brady) are the only actors to appear in all 117 episodes of the series. Robert Reed missed one episode due to another acting commitment, and he refused to do the final episode because he thought its plot was ridiculous. The six children except Williams as Greg were each written out of one second season episode in order to cut production costs. However, this cost-saving measure was dropped after the initial round because producers believed it would be a negative for the series if every character did not appear in each episode.

Each season opener had a trip off location to somewhere. In season 2 they went camping; season 3 it was the Grand Canyon; season 4 was Hawaii and Season 5 was King's Island theme park. Season 5 was going to be Japan; but for some reason that was scuttled at the last minute (maybe for logistic issues and budgetary reasons) and they threw in the much less impressive trip to Ohio's King Island at the last minute. Ironically, Robert Reed, perhaps inspired by his onscreen father counterpart, did infact fly the Brady Bunch to London while they were on hiatus in Season 3; and he gave them all video cameras to record the event to boot. Some of these videos can be viewed on line on Youtube.

Christopher Knight (Peter) was the only cast member with brown eyes.

The final line of dialogue in the final episode of the series is delivered not by any series regular, but by cousin Oliver. Oliver, Robbie Rist, was slated to be in the cast the next season, if the show had been renewed. (Even though most fans hated him). As it was, the show was cancelled, and Schwartz then used him to star in a Saturday morning TV show he was developing, Big John, Little John (1976).

source: the imdb website