Updated response as of December 2016 for Windows 7 installs on Apple computers (laptops and desktops) for those using BootCamp. While this response is aimed more at the Windows 7 installs, Windows 8 versions and later can use this method as well.
BACKGROUND: If you start the BootCamp application within Mac OS, and follow the prompts by clicking the box to download the latest BootCamp drivers (using a Windows 7 iso on the desktop and a formatted USB attached to your Apple laptop/desktop), the install will NOT be able to complete. You will only get as far as the initial Windows 7 install, but on Windows 7 re-boot from BootCamp back into BootCamp, you will NOT have a cursor on-screen (usually at the screen that asks you to choose a language). In addition, your connected wired/wireless mouse and keyboard will NOT work as the Windows 7 BootCamp drivers for the keyboard and mouse will not have been loaded from the previously-created USB. It seems the correct Windows 7 drivers were never, in fact, downloaded; notwithstanding, the BootCamp creation process you did earlier in the process with no hitches.
SOLUTION: To avoid/correct this situation, create your bootable USB as normal using the BootCamp application, but do NOT use the checkbox option to have BootCamp automatically download the latest drivers from the Apple servers. Instead, MANUALLY download the BootCamp driver suite for your particular model device as specified on the table found (scroll down on the page) at:
Install Windows 7 and earlier on your Mac using Boot Camp - Apple Support
Unzip the relevant files to your desktop after download and then copy them over to the root directory of your bootable USB. Then, proceed to use BootCamp as normal by continuing the Windows 7 installation. Your Windows 7 installation will now have the cursor and a working mouse/keyboard to make the appropriate selections and complete the Windows 7 BootCamp process. As a caveat and while not required, using a USB 3.0 and later flash drive (versus USB 2.0) will make your install MUCH faster.