Don't you need to complete your housemanship first?

Yes, it is too early for you to ask.
Please study hard, ensure you have strong basics before you start your housemanship training.
Things have changed and you are not guaranteed a permanent MO post anymore.
Please focus on your finals for now and stop daydreaming.

Before you think about your long term goal, just achieve your short term goal first i.e. pass your final exam.
It is useless to have fantastic long term goal ahead if you fail your exit exam.
Not to mention about completing housemanship (you haven't even exposed to the real life of the training, you are still not sure whether you are suitable with a doctor's life yet and whether your bosses are satisfied with your work)
Hey, that's Mars, please come back to the Earth....(;;)

my question remains....what do you mean by "masters overseas"?...

I think for now the only appropriate slightly-longer-term plan after graduate to make is to think where you want to practise.
If you want to practise in overseas, you may have to study extra (probably double or triple) hard in order to prepare for their entrance exam (unless your degree is readily recognized by their medical councils).

No. just study hard, bring your brain and heart....

Hunther,
In the context of working/practising as medical doctors overseas for local trained, www.pagalavan.com or his books has all the appropriate guidance to your queries or overall scenarios you are/would be in.
UM and UKM main campus med degrees are recognised by Singapore Medical Council who are generally very welcoming so far.
Monash Malaysia med degree is recognised by Australian med council and a small number of her graduates gets offer for internships in Oz, but not for the rest.
Numed med degree is recognised by UK General Medical Council but unfortunately UK immigration rules doesn't permit its graduates into UK Foundation (housemanship) programmes.
Local med degrees other than above are required to pass respective national entrance exams or relevant 'professional memberships' as one of many other stringent (difficult to meet) requirements.
Please google for medical council/boards requirements of respective overseas countries .
Just my 2 sen.