In his review, jwb001 writes "rather than use the umbrella that he found to open the door through the hole, Taylor grabs the real estate agent's umbrella, rips off the fabric, and uses its skeleton to open the door. Completely inexplicable behavior."
Anyone who has seen enough CSI episodes should be aware that they can't always use the original tools to "science" i.e. Recreate events, as this could contaminate the evidence when testing a theory, so by using an alternative umbrella Mac proved how the original umbrella was used and trace can then test it, if necessary, without Mac's test affecting the results. Bear in mind that CSIs generally treat any evidence as though it might one day be presented to a jury and wouldn't want the defence questioning the integrity of their findings.
It also made for a funny moment. In shows like this, you need a few lighter moments to balance out all the killing, rape and other nasty things people do to one another.
Anyone who has seen enough CSI episodes should be aware that they can't always use the original tools to "science" i.e. Recreate events, as this could contaminate the evidence when testing a theory, so by using an alternative umbrella Mac proved how the original umbrella was used and trace can then test it, if necessary, without Mac's test affecting the results. Bear in mind that CSIs generally treat any evidence as though it might one day be presented to a jury and wouldn't want the defence questioning the integrity of their findings.
It also made for a funny moment. In shows like this, you need a few lighter moments to balance out all the killing, rape and other nasty things people do to one another.