You do not need to specify a hash before immediate constants in any instruction syntax (including ARM, Thumb, Wireless MMX, NEON, and VFP instructions). For example, the following are valid instructions:
BKPT 100 MOVT R1, 256 VCEQ.I8 Q1, Q2, 0
By default, the assembler warns if you do not specify a hash:
WARNING: A1865W: '#' not seen before constant expression.
This can be suppressed with --diag_suppress=1865.
If you use the assembler code with another assembler, you are advised to use the # before all immediates. The disassembler will always show the # for clarity.