Lego Star Wars II Glitches - Bobby/Useless Window

Necessities

 * Access to the level 'Betrayal Over Bespin'

Method

 * 1) Go to the outside area where there is an R2 hover gap.
 * 2) Use a character with high-jump to jump round the wall and through the window.

Conclusion
You should go through the window and continue through the floor. Interestingly, the floor acts as a 'mirror line'. There will be a reflection 'beneath' the floor and above the floor although they will be inverted, so that the above-floor version will be upside-down and the sub-floor version will be running the right way up.