Ermm....... why did they need to stay in the tunnel whilst the explosives went off?!?!?!

And what happened to poor Johnson? (The one who set the detonator off at the start)

Sam really had a point about not wanting to go on the mission. He's wise enough to know that hazardous missions and personal involvement don't mix. Was Shane Weston aware that Sam's father was involved? And why did Sam delay telling Mac and Joe about it?

They found Sam in a tunnel, coat off, all sweaty and dusty. When they told him that a communications link had been established, they went back to it immediately. However, Sam took the time to get washed and tidied before taking the phone, which didn't fit in with his air of urgency.

Did someone instruct Joe how to go about giving a hypodermic injection, or did they just leave him to figure it out himself?

It was rather a nice touch that Dr. Loover thought that Joe was Sam.

Was Sam preparing to defy Shane Weston? Weston had ordered him to go on the mission and to take Joe 90 with him. Yet Sam refused to tell them about his father because he felt that Joe 90's talents shouldn't be used for personal reasons. He seemed to forget that there were two other men down there as well.

Those two other men seemed absolutely certain that the drilling was going to cause another cave-in, yet when it finally broke through--nothing.

Either there is a nit here, or Shane Weston was definitely aware that Sam's father was involved. Later, in the episode "Test Flight" Shane made a comment to the effect that WIN was not a rescue organization. Well, what was this, if not a straightforward rescue operation?

Small nit. During the hospital scene, shortly after Dr. Loover wakes up, they show him with his head at an odd angle above the pillow, as though he'd stopped in mid-situp. In the close-up, his head is resting back on the pillow again.

Kudos to Sam Loover's voice actor. The suppressed emotion in Sam's voice as he speaks to his father in the hospital was phenomenal.