In season one's, "Steele in Circulation", it was shown that the windows to the hi-rise offices of Remington Steele actually do open, which should make venting the gas possible.
In a previous episode when a client attempted suicide the windows in the office opened outwards, but in this episode they didn't.
When Laura and Steele are trying to evade their pursuer, they enter a car wash while riding in a taxi cab. All three are shown inside the car as it moves through the wash. But when it's at the end, in a long shot of the car's front, no one is shown in the car. When the car is driven out the driver is once again in full view.