Turbo Assembler - "Forward reference needs override" errors with .386 but not .286?

I'm currently working on a MS-DOS .com file application using Turbo Assembler 1.0. The file starts with the following assembler directives.

 DOSSEG
.286
.MODEL tiny
.CODE
 ORG 100h

This assembles fine so far; however, if .286 is changed to .386 TASM generates error messages "Forward reference needs override". This is somewhat correct, as variables are accessed but defined later.

1. Why don't these error messages appear when assembling with the .286 directive?
2. What can I do to fix these error messages? If, for instance, there is a later variable definition like Variable dw ?, how can this be taken care of in an earlier reference? What is the TASM syntax for this?

Edit: Let me be more specific by giving full examples.

Version 1: Works fine.

      DOSSEG
     .286
     .MODEL tiny
     .CODE
      ORG 100h
Main:
     inc Var  
     ret
     Var dw ?
     END Main

Version 2: Error message "Forward reference needs override" (after enabling 386 opcodes).

      DOSSEG
     .386 ; <-- this has changed
     .MODEL tiny
     .CODE
      ORG 100h
Main:
     inc Var  
     ret
     Var dw ?
     END Main

Version 3: Also complains about "Forward reference needs override", although I believe to have indicated the size of the variable.

      DOSSEG
     .386
     .MODEL tiny
     .CODE
      ORG 100h
Main:
     inc word ptr Var ; <-- this has changed
     ret
     Var dw ?
     END Main