The possibility will always be there wether chasing prey and missing and hitting the glass, digging his home and thinks the bottom is just another hard substance to break through or even seeing something out side the tank it wants to get too (rare)
But if you choose to use glass it's advise that you use a sheet of acrylic that can fit on the bottom of the tank that way he/she/it won't break the glass bottom digging. And don't feed it live food it has to chase. And don't set it next to another fish tank, that way it won't entice the mantis to want to get to the other side.
And do not set up electrical cords and power strips below the tank in case of breakage.