Over the years, reading others code, I encountered and collected some examples of Matlab syntax which can be at first unusual and counterintuitive. Please, feel free to comment or complement this list. I verified it r2006a.

set([], 'Background:Color','red')

Matlab is very forgiving sometimes. In this case, setting properties to an array of objects works also with nonsense properties, at least when the array is empty.

myArray([1,round(end/2)])

This use of end keyword may seem unclean but is sometimes very handy instead of using length(myArray).

any([]) ~= all([])

Surprisigly any([]) returns false and all([]) returns true. And I always thought that all is stronger then any.

EDIT:

with not empty argument all() returns true for a subset of values for which any() returns true (e.g. truth table). This means that any() false implies all() false. This simple rule is being violated by Matlab with [] as argument.

Loren also blogged about it.

Select(Range(ExcelComObj))

Procedural style COM object method dispatch. Do not wonder that exist('Select') returns zero!

[myString, myCell]

Matlab makes in this case an implicit cast of string variable myString to cell type {myString}. It works, also if I would not expect it to do so.

[double(1.8), uint8(123)] => 2 123

Another cast example. Everybody would probably expect uint8 value being cast to double but Mathworks have another opinion.

a = 5;
b = a();

It looks silly but you can call a variable with round brackets. Actually it makes sense because this way you can execute a function given its handle.

a = {'aa', 'bb'
'cc', 'dd'};

Surprsisingly this code neither returns a vector nor rises an error but defins matrix, using just code layout. It is probably a relict from ancient times.

set(hobj, {'BackgroundColor','ForegroundColor'},{'red','blue'})

This code does what you probably expect it to do. That function set accepts a struct as its second argument is a known fact and makes sense, and this sintax is just a cell2struct away.

Equvalence rules are sometimes unexpected at first. For example 'A'==65 returns true (although for C-experts it is self-evident).

About which further unexpected/unusual Matlab features are you aware?