Lethal Weapon 4 (1998) - 3 questions

Question: I wonder, what was the point of having a gunfight with the armored man at the beginning of the film?

Answer: It was put in the film to introduce the concept of Rianne and Lorna being pregnant and to bring in the joke about the news article about Roger, not to mention giving the film an action-heavy opening.

Question: In the beginning of the movie when the tanker truck gets blown up, why does the fully intact truck just get launched straight up with flames below it? The source of the explosion would be the truck itself, so when ignited, the truck should have simply been blown up into a million pieces, not launched straight up fully intact.

Answer: This was most likely done just to make the scene look that much cooler. Movies do things like this all the time.

Question: Something I really don't understand about the ending. Riggs is looking over his former wife's grave when his beeper tells him that Lorna is expecting their baby. He races to the hospital and there she is about to give birth. So who drove Lorna to the hospital? Can't have been Riggs as he wouldn't have left at a time of need just to see his wife's grave. Doubtful that Lorna drove herself, and no relatives were there (as we see at the end). So what other explanation is there?

Answer: She could have taken a taxi or an ambulance, or even driven herself. A neighbor or friend could have taken her who didn't stay after she was admitted. She might have already been at the hospital for any number of reasons - doctor's appointment, already admitted for bed rest prior to labor, etc. etc. etc.