Here is some information that I consider important about the episode 13 flight:
1. The entire episode was built around it, because SQ481 only flies on Mondays, Wednesdays, and Fridays. In order for the race to get this nonstop flight(highly desirable because the race designers hate connecting flight for going to the Finish Line) they had to assure that the tasks would occupy the teams until after 1030, which is when the last flight to Johannesburg that could catch a connection to Singapore on Sunday July 22 would leave.
2. All that frenetic activity around CapeTown was merely to make sure no team could get to the airport too early. Marc and Rovilson got to the first task at the District Six Museum presumably just after it opened at 8am. Sunset was 6pm at CapeTown on July 22 and I think Pamela and Vanessa arrived at the airport after completing all those tasks at about 6pm judging from the clouds.
3. All teams would have gotten a hotel near the airport.
4. SQ481 departed at noon on July 23 and arrived Singapore at 0525 July 24. This had the benefit of getting the teams to Sentosa Island Jantong Beach long before the public would have wanted to be there.