South Africa was banned from the Olympic Games in 1960 due to apartheid, but reinstated in 1992 and participated in the Barcelona games. David should be able to compete for his home country and not need to immigrate to Australia; however, it is possible that he or his coach believed another ban might be imminent and planned accordingly.
David's coach describes South Africa as being in a state of "civil war". The early nineties were marked by unrest, including terrorist attacks and retaliation by the government; however, the violence is not generally regarded as having risen to the severity or organization of civil warfare.
When Betty Heslop writes the first check to "cash" for Muriel to buy cosmetics, it is dated 12-1-1994. When Muriel hands her father a check for $5,000 near the end of the film, that check is dated 2-11-1992.
While Muriel and Rhonda are imitating ABBA on stage, Tania and Nicole get into a knockdown fight and the entire table is disrupted. When we cut back to Muriel and Rhonda, the girls still sitting there just watching. We can see the backs of their heads, and their dates are standing enjoying the show as before.
When Muriel is trying on a wedding dress in the shop, and is admiring it in the full-length mirror, to the right in the mirror, you can clearly see a crewmember standing there, before quickly darting out of the reflection.
When Muriel hands her father a check at the end of the film, you can see it's for $5,000. She says, "That's not all of it..." and in fact it isn't, because the amount was established earlier as $12,000.