Remember they weren’t far away from Vegas at the start. A flight to LA from there is what…an hour?
In the book, he’s in Baker CA when he calls his attorney. That’s about 100 miles from Vegas, so maybe an hour drive time in the Shark? But after he calls him, he stops for a beer or six in Baker before leaving to go back to Vegas, stops somewhere in the desert to test out the .357 on an iguana, stops at a pharmacy on the outskirts of Vegas for tequila, scotch and more ether, then goes to the airport car rental to trade in the Shark for the White Whale. Plenty of time for Dr. Gonzo to catch a flight from LA and slip some LSD to poor Lucy.
In his June 15, 1971, letter to Random House’s Jim Silberman (collected in Fear & Loathing in America), Thompson says:
“The only thing that vaguely alarmed me about your letter was your statement, to wit: ‘You know, it was absolutely clear to me reading Las Vegas that you were not on drugs…’. This is true, but what alarms me is that Vegas was a very conscious attempt to simulate drug freakout - which is always difficult, but in reading it over I still find it depressingly close to the truth I was trying to re-create. To this end - and right after your letter came - I ate a bunch of mescaline and went to a violent, super-jangled car race last weekend with Lucian Truscott from The Village Voice, and I was relieved to find that we - along with about 10 other people - experienced the same kind of bemused confusion with reality we had to deal with that Raoul Duke & his attorney had to cope with in Vegas. We were completely involved with what was happening - but our involvement was not so much on a different level as from a different point of view than the people in the grandstand around us. A man behind us was more excited; a man in front of us was more alarmed at the behaviour of a truckload of freaks who seemed more scrambled than we were - but our overall approach to the race and the scene was consistently Strange, in the same sense that I tried to make that Vegas thing consistently strange,”