TAKOBOTO

If unexpectedly there is anything , 〜
If there is anything unexpected, please call here.

Add formation 

まさかのばあい、ここにでんわしてください。

If there is anything unexpected/For the unexpected , please contact to this place.

まさかのとき、すぐおしらせください。

If there is anything(unexpected) ,please let me know at once.

まさかのときにはちょちくにたよればよい。

In an emergency you can fall back on your savings.

まさかのときにそなえてちょちくせよ。

Keep something for a rainy day.

まさかのときのともこそしんのとも。

Friend in need is a friend indeed.

まさかのときにはあなたをたすけてやろう。

I'll stand by you in time of need.

わたしのかぞくはてんきがよかったのではなみにいったら、まさかのきゅうなあめがふりだした。

When my family went to flower viewing because the weather was nice, a sudden unexpected rain began to fall.

Always come with 「まさかの場合、〜」、「まさかの時、〜」

誠

In #5842, まさかの場合 should preferably be まさかの時は and in #5843, まさかの時 should be まさかの時は

bamboo4

There are 19 まさかの時 examples in WWWJDIC
http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?1Q%A4%DE%A4%B5%A4%AB%A4%CE%BB%FE_0__
which can be "borrowed" as necessary. In WWWJDIC examples the Japanese is usually good, but the English is sometimes dodgy.

Paul Blay

a lot of those examples are duplicates, but i added the best. FYI the link on this page to "Search big database for more examples of まさかの〜" searches the same WWJDIC example database.

dc

Wouldn't example [#5843] be more succinctly translated as, "If there is anything unexpected, please call."? It's not really necessary to include the "to this place" (or better - "here").

lonesoullost

｢まさかの時｣を「何か在ったら」と同じ意味で把握しても良いですか。

ppmohapatra