Resin kits may
occasionally have small air bubbles in the parts. If these are on the back of the
part and will not show on the finished model, there is no need to worry
Air bubble holes that will show may be filled with a medium super glue (gap filling) and the patch sanded or filed smooth. A good filler for larger holes or gaps is a mixture of gap filling (medium) super glue and either talc or corn starch. File or sand the patch as soon as it is hard to the touch; as the mixture will become harder than the surrounding resin.
If the bubble is in an area that is not easily repaired, contact the kit manufacturer for a replacement.