When invisible Buffy is moving the coffee mug at the social worker's office the first time, one can see the shadow of the arm placing the mug outside the screen and than retreating.
When invisible Buffy is going through the files at the social worker's office, one can briefly see her fingers grabbing her sister's file.
Spike's bedroom is in a cave under his crypt. Yet when Xander walks away from Spike's bedside and leaves the crypt the crypt door can be heard closing almost immediately. To do this Xander would have had to walk several feet, go up a ladder, then walk nearly the length of the crypt to reach the door. Xander would have to be impossibly fast to do this, as there is no door between Spike's bed and the main crypt entrance.
The keys on Doris' typewriter are being pushed at random, some keys simultaneously. The printout the supervisor reads should have had nothing but gibberish on it.
Every time that the invisible trio grabs or holds Willow the sleeves of her sweater are smooth. The fabric should still crease or rumple, invisible hands or not.
When Buffy is cutting her hair the bra strap on her right shoulder keeps moving back and forth.
Invisible Warren is knocked into the tub filled with colored balls yet you still can't tell he's there until he becomes visible again. He still has a body that takes up space,invisible or not, so there should have been a hole or gap in the balls.
Xander is looking down at the sidewalk when he bumps into the invisible fire hydrant. Even though the hydrant itself is invisible, the hole in the sidewalk and the water pipe under the hydrant should still be visible.
In the scene with Willow and Xander on the street the tire track from the van has a perfect mark of the tire tread in the middle. The entire track should be streaked as a tire spinning on pavement would obliterate any tread mark.
The sign in the window of the store the Trio are about to enter says "Bikini Wax Wednesdays" which is the day that this episode takes place.
Willow is trying desperately to quit magic in this episode, and we see her straining not to use it to move a book or to speed up a computer search. But when she sneaks into the Trio's lair and gets taken hostage she makes no attempt to use it at all. I know it's a plot point that the Trio has Willow at the arcade, but it seems highly unlikely that a powerful and magic-addicted witch like Willow would not try to use her power to defend herself.
After Buffy throws the second air hockey mallet at Warren another mallet can be seen still on the table near where Buffy was standing, but when we see the table again during the fight it's disappeared.
When Buffy types on Doris' keyboard you can clearly see the wires used to pull the keys down if you look to the left of the keyboard.
In the scene where Anya and Xander discover that the pylon is turning into a 'pudding' like substance, what looks like the edge of a light reflector can be seen on the right hand side of the screen.
In the beginning of this episode, Buffy throws Spike's lighter in the box with Willow's magic accessories. Later on, Spike reaches into Buffy's pocket and pulls the lighter out... how did it get there?
When Buffy goes gets the pizza box, she places it on the counter. In the next cut, you don't see it on the counter anymore.
When Spike and Buffy are talking in the kitchen there are rays of sunlight in there. It looks like its beaming not only on Buffy, but Spike too.
Spike: You should leave. Get dressed, if you can find your clothes, and bugger off. Because if I can't have all of you, I... (looks down) Hey, that's cheating.
Buffy: I know what that looks like but I - I swear it's not what it looks like. It's magic weed! It's not mine.
Buffy: So you three have what, banded together to be pains in my ass?
At the end of the episode, with Buffy and Willow sitting on the curb talking, the music playing softly in the background is Trespassers William song "I Know". The song begins "I know I'll never see you..." which can refer to the invisibility theme and to Buffy's love life.
This is David Fury's directorial debut in which he also wrote, as it must be fitting that he actually directed his wife Elin Hampton in one scene at the Social Services Office. He and Elin co-wrote Season 2's "Go Fish" together as well.
When Invisible Buffy is leaving the social services center she whistles a few bars of Going Through The Motions, her "theme" music from the musical episode Once More, With Feeling.
This is the first episode without Amber Benson (Tara) since last season's 'Into The Woods'. In fact, this marks only the sixth episode without the character since she was introduced in season 4's 'Hush'.
Xander asks Invisible Buffy if she has been ignored lately, referring to the causes of Marcie's invisibility in season 1's 'Out of Mind, Out of Sight'.
It took nearly a month to wrap up this episode, due to the ongoing aspects of Invisibility.
Invisible Buffy (at the Social Services office): Yahtzee!
Yahtzee is a popular dice game where players roll 5 dice and get points for different combinations. The highest roll (50 points) is called a "Yahtzee" and players shout it when they roll that combination.
Invisible Buffy (to Xander, in the Magic Box): S'Alright
Reference to the tag line of Senor Wences, a Spanish ventriloquist popular in the US during the 1950s and 60s.
Dawn: Kokopelli?! No! I love him! And he was Mom's. Why do we have to get rid of so many things I like?
Kokopelli is found in a number of Native American cultures, being especially prominent in the Anasazi culture of the "Four Corners" area. The figure represents a mischievous trickster or the Minstrel, spirit of music. Kokopelli is distinguished by his dancing pose, a hunchback and flute.
Warren: Oh, cheer up, Frodo.
Frodo Baggins is the hero of the epic fantasy novel, Lord of the Rings. Frodo is a Hobbit, which are known for being short, like Jonathan (they are called Halflings by most of Middle-Earth). Frodo is somewhere around 3 feet tall, reminiscent of Buffy's comment in 'Earshot': "He's like, three feet tall!".
Andrew: I pictured something cooler. More ILM, less Ed Wood.
ILM stands for Industrial Light and Magic, a division of George Lucas' production company LucasArts. The company is arguably the most prestigious visual effects company in the world. Its current incarnation dates back to work on The Empire Strikes Back in 1980, although the group that worked on the original Star Wars used the name as well.
Ed Wood (Edward D. Wood Jr. 1924-1978) was a sci-fi writer/director/actor from the 1950's and 60's who cluelessly made some remarkably bad films, including 1958's Plan 9 from Outer Space, often called the worst movie ever made.
The making of the movie was immortalized in the 1994 film Ed Wood, directed by Tim Burton and starring Johnny Depp. The film also features Juliet Landau, who plays Drusilla on Buffy, in a small role, and won her father, Martin Landau, an Oscar for Best Supporting Actor.
Buffy: Xander and Anya are working on it.. 'Mulder-ing' out what happened.
Fox Mulder is one of the main characters on the FOX sci-fi drama show The X-Files who, if you don't know, solves cases involving paranormal phenomena.
Visual: "All work and no play makes Doris a dull girl".
The way Invisible Buffy messes with the social worker is reminiscent of the Stephen King novel and Stanley Kubrick film The Shining. Jack Torrance writes the words "All work and no play makes Jack a dull boy" when he starts to go crazy from cabin fever; and the ghosts of the hotel encourage him to "Kill. Kill. You know you want to".