Worst epic science fail you have seen in sci-fi?

[Drashner1]

Star Trek: 
"Lets use the deflector to shoot at the Borg" 
"Lets use the deflector to heal a space creature"
"Lets use the deflector to hack the mainframe"
"Lets use the deflector to trick the orbital defenses"
"Lets use the deflector to manipulate space time"
"Lets use the deflector to collapse the black hole"
"Lets use the deflector to cook dinner"
"Lets use the deflector to deus ex machina all the things"






DEFLECTOR

At least some of these might work if we presume that Federation technology is highly reconfigurable (which numerous episodes across the entire franchise strongly indicate that it is) and depending on what principles it operates on. However, in support of your point, some of the applications are kind of out there (in polite phrasing) and the sheer use of the dish as a deus ex machina Maguffin starts to near the point of satire.

Of course, the deflector dish pales in comparison to 'subspace' or the 'particle of the week' and all the ways each of these two concepts are used to handwave virtually anything that needs/wants doing for the sake of the plot.

Todd