I show the first 1:51 minutes of the clip and ask “What’s the value of $50 (not) received 53 years ago? The interest rate is 5%.”

The answer, of course, is FV = $50 * 1.05^{53} = $663.75

I revisit the same clip when I talk about the difference between annual percentage rates and effective annual rates. The question now becomes “What’s the value of $50 (not) received 53 years ago? The interest rate is 5%, quarterly compounded.”

I then ask my students how they interpret the 5%: is it an APR or an EAR? Depending on the assumption, you get different results:

Annual compounding (original question)

FV = 50 * 1.05^{53} = 663.75

Quarterly compounding if 5% is an EAR

Quarterly rate r: (1+r)^{4} = 1.05 <=> r = 1.22722%

FV = 50 * 1.0122722^{(53*4)} = 663.75

Quarterly compounding if 5% is an APR

Period rate r = 5%/4 = 1.25%

FV = 50 * 1.0125^{(53*4)} = 696.17

Since interpreting it as an EAR gives the same result as annual compounding, it only makes sense to interpret it as an APR (why would you mention quarterly compounding otherwise?).

I then show the clip from minute 1:51 to 2:13. It looks like the Hollywood screenwriters were right about the future value or about the compounding, but not both. The life lesson here is: Don’t rely on Hollywood script writers for financial advice.