In the previous episode, Vaughn instructed Sydney that she was to dial 3 digits on the dummy telephone to gain access to the secret CIA facility. When she enters the code in this episode, you can clearly hear *four* buttons being pressed.
When Sydney is in Siberia, her ponytail can be seen poking out over her left shoulder; in the next shot the hair is gone.
When Will is being hypnotically regressed, in one shot the electrode on his left temple peels almost completely off. The next time it's seen it's firmly re-attached.
When Sydney is escaping the ducts during the rocket launch, a shot of her just coming out of the ducts reveals the rope that is pulling the cart she is riding on.
Francie tells Sydney off for 'Waving a beer' in Will's face. But Francie is doing the same thing essentially, as Will is helping her in her restaurant where alcohol is served.
When Marshall is explaining the luge, he tells Sydney she can go 150 miles an hour, but also that she can travel 2 miles in 12 seconds (600 miles an hour).