Continuity mistake: Near the beginning of the episode, Roy is eating & drinking while the phone is ringing. Eventually he picks it up, then Moss comes in and throws him a muffin. Just before Moss walks in, Roy's coffee cup is on his right on the desk. The next shot, as he catches the muffin, the cup has instantly moved to his left. Afterwards, the cup is back on his right. (00:03:20)
Continuity mistake: During the party down in the basement, after Moss has told the embarrassing Amsterdam story, Roy comes back in the room and realises nobody's laughing. He walks up to Moss and says, "What story did you think I meant?" Roy has a beer in his left hand. The next shot, within seconds, he's shaking Moss by the shoulders with both hands. There was no time frame for him to have put the cup of beer down. (00:22:05)
Continuity mistake: When Denholm is holding the picture of the A-Team, he is holding it on the left side of the frame. When it cuts to him putting it down, he is holding it on the right side of the frame.
Continuity mistake: Jen's tights change throughout the episode. Sometimes she is wearing black tights, other times she is wearing pale/no tights.
Continuity mistake: When Moss asks if Roy is OK, it shows Moss holding his cup by the handle. In the close-up shot of Moss, his grip is on the cup itself. In the next shot he is holding it by the handle again.
Answer: It's a joke on the "118" numbers in the UK. 118 numbers were used for directory enquiries and adverts for them on TV always tried to give a way to easily remember one for a particular company. The fake ad in the show takes it to the extreme. People in the UK do not use "911", the point of the joke was that Roy had forgotten "999" while saying it was easy to remember.