Revealing mistake: Bad guy is shot but can be seen breathing afterwards on the ground. At the start of the next episode, he was shown to be shot in the head. (00:40:38)
Continuity mistake: The clock just tells the viewer that it is 4:40am. Sen. Palmer interrogates his son about the rape of his daughter. In the room, there is a clock that shows 4:57am instead. (00:27:43)
Day 5: 1:00 AM - 2:00 AM - S5-E19
Factual error: When Chloe is at Bill's, she brings up the details of the diplomatic flight, and it shows the aircraft as a Boeing 757-200. This is a twin-engine aircraft, but the one shown is a tri-jet.
Day 6: 8:00 AM - 9:00 AM - S6-E3
Visible crew/equipment: After Tom tells President Palmer that Sandra has been arrested, when it cuts to the interior shot inside the car with Agent Samuels in the front passenger seat, the camera pans toward the rear passenger window showing all the protesters outside. In this shot there's a reflection of the camera operator's leg, wearing shorts, white socks and sneakers, and who is sitting where Sandra should be.
Day 6: 8:00 AM - 9:00 AM - S6-E3
Visible crew/equipment: When Jack pulls over at the side of the road, as he informs Curtis that Assad is two miles ahead on the service road, the red T-mark is visible on the ground where the two men will stand.
Day 8: 7:00 A.M. - 8:00 A.M. - S8-E16
Character mistake: When the exit guard puts Dana Walsh's ID card in the computer it comes up with "apprenhend on site", which should obviously be "apprehend on sight". (00:09:45)
Day 6: 3:00 PM - 4:00 PM - S6-E10
Visible crew/equipment: While Bill, Nadia, and others begin watching Turner's team move toward Gredenko's presumed location on the live video feed, in the next shot facing Bill and Nadia, the T-mark quickly becomes visible at the bottom of the screen, near Bill's feet. (00:29:50)
Day 7: 9:00 AM - 10:00 AM - S7-E2
Visible crew/equipment: While FBI agents are searching for the sniper Jack tells Renee there must be a bad agent, and just as he warns her about who she lets in, the green T-mark is visible on the ground. (00:05:35)
Day 6: 12:00 AM - 1:00 AM - S6-E19
Visible crew/equipment: After Tom tells the VP that he could authorize ancillary agencies to join the search to find Jack, he and Karen leave the Oval Office, and in the next shot facing Lisa as she walks toward Noah, the yellow T-mark is visible on the rug at the bottom of the screen. (00:11:05)
Day 6: 12:00 PM - 1:00 PM - S6-E7
Continuity mistake: At the very end of the previous episode (approx 11:59 AM), Jack and Phillip are chained at the back of the van, and in the closeup Jack's handcuff double bar faces up on his right wrist. This moment is shown in the recap at the start of this episode. When the van reaches the dump site (approx 12:07 PM), Jack and Phillip are unchained and now Jack's handcuff single bar faces up on his right wrist. (00:01:55 - 00:07:55)
12:00 Midnight-1:00 A.M. - S1-E1
Continuity mistake: Kim Bauer has a full set of glittery pink disco nails on episode one (midnight) but then these are not visible at all in most episodes. In the 2pm episode her nails look clean/natural in nearly all the shots, apart from during the phone call with Rick where traces of pink glitter can be seen. I know she's had a very rough night but it doesn't explain the amount of damage her nails have sustained.