We will have to wait for preview screencaps and the written promos for the finale. It will be a busy week. When they have used helicopters in the past to transport teams........they always have taken them to another airport and then the teams drive /taxi from there. So probably a small, general aviation airport in the area of the LA basin/SoCal area that they have the tasks for the finale.
Towered general aviation airports
Brackett Field (IATA: POC, ICAO: KPOC) is in La Verne.
Camarillo Airport (IATA: CMA, ICAO: KCMA) is in Camarillo.
Chino Airport (IATA: CNO, ICAO: KCNO) is in Chino.
El Monte Airport (IATA: EMT, ICAO: KEMT) is in El Monte.
Fullerton Municipal Airport (IATA: FUL, ICAO: KFUL) is in Fullerton.
General William J. Fox Airfield (IATA: WJF, ICAO: KWJF) is in Lancaster.
Hawthorne Municipal Airport (IATA: HHR, ICAO: KHHR) is in Hawthorne.
Oxnard Airport (IATA: OXR, ICAO: KOXR) is in Oxnard.
San Bernardino International Airport (IATA: SBD, ICAO: KSBD) is in San Bernardino.
Santa Monica Airport (IATA: SMO, ICAO: KSMO) is in Santa Monica
Southern California Logistics Airport (IATA: VCV, ICAO: KVCV) is in Victorville in San Bernardino County, far north-east of the city.
Van Nuys Airport (IATA: VNY, ICAO: KVNY) is in the San Fernando Valley. It is the world's busiest general aviation airport.
Whiteman Airport (IATA: WHP, ICAO: KWHP) is in the northern San Fernando Valley.
Zamperini Field (IATA: TOA, ICAO: KTOA) is in Torrance.
Riverside Municipal Airport (IATA: RAL, ICAO: KRAL) is in Riverside
Non-towered general aviation airports
Apple Valley Airport (IATA: APV, ICAO: KAPV) is in Apple Valley
Cable Airport (IATA: CCB, ICAO: KCCB) is in Upland.
Catalina Airport (IATA: CIB, ICAO: KAVX) is near Avalon, Santa Catalina Island.
Compton/Woodley Airport (IATA: CPM, ICAO: KCPM) is in Compton.
Corona Municipal Airport (IATA: AJO, ICAO: KAJO) is in Corona.
Flabob Airport (IATA: RIR, ICAO: KRIR) is in Riverside.
Perris Valley Airport (FAA LID: L65) is in Perris.
Redlands Municipal Airport (IATA: REI, ICAO: KREI) is in Redlands.
Rialto Municipal Airport (FAA LID: L67) is in Rialto.
I also found a list of 61 federally registered heliports.