Dana Walsh, President Omar Hassan, the late Farhad Hassan, and Jack Bauer are the names in the previouslies freeze-frames. Oddly, Marcos Al-Zacar doesn't get one, even though he's the guy who made half of these previouslies happen to begin with.
Marcos is of course still barricaded inside the hyperbaric chamber at the hospital. In addition to the intercom camera Marcos disabled at the end of the last hour, there's a bulb-style overhead camera mounted in the ceiling, watching Marcos do his thing. That thing, of course, is tinkering with the guts of his vest's electronics while referring to a complex circuitry diagram that he drew on the wall during the previouslies. So when Samir told Marcos he would "walk him through" modifying the detonator, what he meant was he would somehow download the required schematic directly into Marcos's brain over the phone? Dude, if the IRK has that kind of technology, who needs nukes in the first place? As Marcos continues fiddling with the wires, his vest gives a little beep and an LED light comes on under his left shoulder. That either means something to do with the bomb or Marcos's internal hard drive is spinning.
In the hallways outside, a tech geek in CTU armor is giving Kiefer a rundown on the chamber. It's one-inch steel all around (okay, so I was off by a factor of twelve) and air and power systems are "internal," whatever that means. Are we supposed to believe that the pressure controls are also operated from inside? Wouldn't that mean that anybody undergoing treatment in there would either have to be accompanied by a doctor or technician, or run the machine themselves? Maybe the magic of the hyperbaric chamber is that people inside it can instantly become experts on how to work anything, which would also explain Marcos's circuitry diagram. It would also explain why, for this entire episode, nobody ever hits on the idea of simply pumping out enough air to render Marcos unconscious. And don't tell me this chamber can't do that, because otherwise there'd be no reason for the door to swing outward instead of in. CTU would still have to get in there somehow, but at least it would buy them some time during which Marcos wouldn't be working on the bomb because he'd be too busy lying on the floor drooling pink foam. The geek adds that the atmosphere inside is probably oxygen-rich, which increases the risk of fire. Probably? Gosh, isn't it just CTU's luck to have to deal with this problem in a hospital without any staff to ask questions like this. As far as getting Marcos out, it's going to take forty minutes to drill through the steel, using a low-speed drill to avoid sparks and the attendant risk of explosion. Taking people alive is such a hassle sometimes.