Revealing mistake: When Austin enters the bathroom at the casino, keep your eyes on the door during the scene - it opens by itself before closing. (00:31:10)
Revealing mistake: During the honeymoon sequence at the end of the film, if you look at the right top of the flowers in the vase during the "flowers covering nipples" bit, you can see a bit of red duct tape covering Liz Hurley's nipple from behind the flowers. (01:22:20)
Revealing mistake: In the scene at Alotta Fagina's penthouse, you can see the side of her swimming costume as she gets in the jacuzzi - she's meant to be naked. (Fullscreen only). (00:44:00)
Revealing mistake: In the scene where Austin and his allies burst through the big blue door, right before "Secret Agent Man" begins playing, the door explodes, and you can clearly see that it's made out of wood, even though it's painted to look like and is meant to be metal. This mistake is even mentioned in the director's commentary on the Austin Powers DVD.
Revealing mistake: When Patty O'Brien (the Irish assassin) fails to strangle Austin in the restroom, Austin grabs him and shoves his head in the toilet. If you look closely, right before O'Brien's head enters the toilet, the back of his hair is already wet. (00:32:30)
Revealing mistake: During the Honeymoon scene when Austin and Vanessa are both naked, Austin sits down on the couch - I think it's the computer that covers him up. But if you look closely, you can see the G-string he's wearing. It's flesh coloured and hard to see, but it's there.
Revealing mistake: When Austin encounters the fem-bots, the main one begins to gas him. Then camera pans to her back, revealing the hoses emitting the gas.