Peach, here is what I think is going on in each cap. It's listed by team/location/sound. Anything with a question mark is unknown or I'm not sure of. Note the "rip sound" refers to the "rip" sound made as the clue is being opened.
Caps:

1: Sam & Renae/ St Pauls Ruins in Macau/Rip sound. They don’t say anything but it should be “Fly to South Africa”.

2 & 3: Luke & Jeff/??/Rip sound

4: ?

5: Mel & Alana or Sam & Renae/??/ Rip sound

6: ?

7: Dave & Kelly/ MCG (start line)/Rip sound, Should say “Fly to Lombok.”

8: Alana & Mel/??/ “Fly to Cape town.”

9: Sam & Renae?/??/Rip sound

10: Joey & Richard?/??/Rip Sound

11: Kelly & Dave/ St Pauls Ruins, Macau/ “Fly to South Africa”

12: Anastasia & Chris/ Indonesia/??

13: Joey & Richard/ St Pauls Ruins, Macau/ “Fly to South Africa”

14: Anastasia & Chris/ MCG (start line)/ Should say “Fly to Lombok, Indonesia.”

15: Anne-Marie & Tracey/ Vietnam Pit start??/ “Fly to Hong Kong”

16: Matt & Tom?/??/??

17: Sam & Renae/ St Pauls Ruins, Macau/ “Fly to South Africa”

18: Ryot & Liberty/ Indonesia Pit start??/ “Fly to Vietnam”

19: Alana & Mel/ Indonesia Pit start??/ “Fly to Vietnam”

20: Dave & Kelly/ MCG (start line)/ “Fly to Lombok.”

21: Jeff & Luke/ ??/ ??

22 & 23: Dave/ Vietnam??/??

24: Jeff & Luke??/ Saigon Opera House??/??

25-28: Alana & Mel/Saigon Opera House??/ Rip sound, ”Another flight. Taxi!”

29-30: Anne-Marie & Tracy/Vietnam??/Voiceover: “We’d been in the city for about 30 mins and we’re flying out again”

31: ??/??/Voiceover: “We’d been in the city for about 30 mins and we’re flying out again”

32-33: Nathan & Tyler/Taxi/Voiceover: “We’d been in the city for about 30 mins and we’re flying out again”

34: Alana & Mel/ Confessionals/ We’d been in the city for about 30 mins and we’re flying out again”

35-36: Matt & Tom??/Vietnam??/??

38: Grant/??/“Nearly 50000 Km, across Africa, Europe, Asia & the Middle East. 11 unforgetable Aussie teams will race around the planet”