When recording his conversation with Sally in his motel room, Mr. Hallet says into his recorder that the date is in March, when they're not far past the summer solstice, which would put them in June.
Officer Hallet is supposed to have one green and one blue eye. However, the moment Sally notices this is the only moment it happens. During the rest of the movie, both eyes are blue.
Officer Hallet comes for breakfast, and when Sally first comes down the stairs her hair is straight. However, in the next shot, and all subsequent shots, her hair is curly.
When Sally is outside cutting down the rose bush, her jeans have dirt marks on the knees. When she goes inside to get her sister, her jeans are clean.
When the witches jump off the roof, they are in a different order when they land than when they were on the roof.
The end credits misspell the name of the town of Coupeville, Washington (whom the producers thank). They leave off the first "e".
The sisters have a 'Dualit' toaster in their kitchen. At one point the toaster makes a loud 'ping' noise and the toast shoots out. That model of Dualit doesn't do that. It has a lever that must be used to manually lift out the toast. It doesn't ping either; it has a dial that counts down the seconds with a clockwork grind, and then just stops. However, nice as that information is, it's clear in the scene that the popped-up toast was triggered by magic as an invented excuse.
After the exorcism Sally and Gilly take the cauldron from two women. It has just been taken from the stove and they are holding it with cloths. When they go to tip it up, Gilly holds the bottom of the cauldron in order to tip it up.
When Gillian first leaves, right before she and Sally cut their hands, she asks for her boyfriend's pocket knife. He clearly reaches for his pocket before she mentions what she needs.
Sally talking on the phone when she is calling the other mothers.
After Sally has put her letter to Gillian in the mailbox, and she is running back into the house to answer the phone, you can see a piece of equipment that is projecting light on Sandra.
When casting the resurrection spell, both Gillian and Sally mispronounce the name of the witch goddess, Hekate (Hecate). They pronounce it "Heck-tate" when it's properly pronounced "Heh - cah - tee".
The Aunts tell Sally they are taking the girls to the solstice, and they return the morning after Jimmy dies talking about it. There are two solstices per year: summer and winter. It is obviously summer time by the way everyone is dressed on that night and the following days. The summer solstice is in late June. When Sally is chopping down the rose bushes that grew overnight by Jimmy's grave, Detective Hallet comes and comments that it's early for roses. Actually, in New England, June is right on target for roses. Does it say where they are located? It's filmed in the Pacific Northwest, though it is also the perfect season for roses.
When Gillian describes Jimmy to Sally (he reminds her of cowboy Dracula), she says that Transylvania is located in Bulgaria. It's in Romania.
When Gillian is in the car before she goes to see Sally, she sings a song by Joni Mitchell. Gillian says "I would drink a 'piece' of you" even though the title and the words are "A Case of You".
When the mothers are meeting to learn who is named to the different places on the phone tree they are all surprised when Sally is named at the top of the tree. She should have already been named lower on the tree, most likely at the lowest spot due to her unpopularity within the community.