Always initialize variables
In C-Script, uninitialized local variables (like var myvar;) were automatically initialized to zero. Not anymore. You now should to either initialize variables in the definition (like var myvar = 0;), or leave them uninitalized only when their inital value does not matter. Because structs can not be initialized in their definition, use the zero() macro (defined in acknex.h) for initalizing local or global structs to zero, and vec_zero() for initializing vectors consisting of 3 vars:

VECTOR speed;

vec_zero(speed); // initializes the VECTOR "speed" to x=0,y=0,z=0

For migration and testing, lite-C can automatically initialize all local variables to zero with the PRAGMA_ZERO definition. If you add

#define PRAGMA_ZERO // initialize variables

at the beginning of your script, all uninitialized global and local variables are set to zero. This slows down function calls a little, so it's preferable not to to use PRAGMA_ZERO in your final version. Global variables and structs are still automatically initialized to zero in lite-C, but you should make it a habit to give their initial values nevertheless.
Check vectors and arrays
In C-Script, we could use x, y, z elements for var arrays. In lite-C there's the VECTOR struct. So for using x, y, z elements, and for calling engine functions that expect VECTOR* pointers, you now need to define a VECTOR* rather than a var[3]:

var vSpeed[3] = 10,20,30; // C-Script
var vSpeed[3] = { 10,20,30 }; // lite-C - address with [0], [1], [2]
VECTOR* vSpeed = {x=10;y=20;z=30;} // lite-C - address with .x, .y, .z

!! The wrong use of arrays can lead to trouble when converting a script. In C-Script, the name of an array was equivalent to its first element; in C it's the address of the array. So the following code has correct syntax, but leads to different results in C-Script and lite-C:

var my_vector[3];
...
var x = my_vector; // C-Script: x is set to the first array element
var x = my_vector; // lite-C - wrong: x is set to the array pointer!
var x = my_vector[0]; // lite-C - correct: x is set to the first array element

Declaring global struct pointers (f.i. VECTOR* v = {x=1;y=2;z=3;} ) //inside functions will now issue an error message.

BTW, in Lite-C you don't need to allocate the VECTOR* pointer.
This at least works:
Code:
VECTOR* sca;
vec_zero(sca);
ent_create(CUBE_MDL, sca, NULL);

Du meinst ohne das Sternchen:
VECTOR BONE_VEC;
ANGLE BONE_ANG;
EDIT:
BTW, in Lite-C you don't need to allocate the VECTOR* pointer.
This at least works:

this will work...